What making grounds for this theory are the facts that the construction, which has been made just before or after the Great Pyramid, called mastabah is a tomb of a king or the aristocracy, and that a Greek historian of the 5 B.C. named Herodotus stated "The each of the three pyramids of Giza are for Khufu, Khafre, and Menkure respectively." Additionally, the discovery of the marks of stonemason found in the four spaces above the Weight relief Chamber is also said to be supporting the theory.

Question
However, this theory is bringing up the following doubts. It seems that there is no other historian besides Herodotus who has expressed such an idea. Moreover, in regard to the stonemason's marks found by Vyse, there seems to be some arguments about its credibility as it is unclear why the name of such an awe-inspiring Great Pharaoh, King Khufu, has been misspelled, and how come the letters written to praise the Pharaoh are so clumsy and not expressing a feeling of respect.

Furthermore, the theory of Pharaoh's tomb cannot explain the structure of the Great Pyramid at once. It says that the burial chamber originally had been at the Subterranean Chamber located deep under the rock bed, serving as the foundation, at the time of construction, but the plan has been changed suddenly "while the Subterranean Chamber was under construction" and the burial chamber was rearranged to be moved to the Queen's Chamber. But then the plan was changed once again "while the Queen's Chamber was under construction," and the burial chamber ended up being placed in the King's Chamber after all. The reason why the plan has been changed in the middle of the construction is that you just have to think this way as long as those chambers exist, or otherwise, this theory would not hold good. The King Khufu must have been a kind of person who would change his minds very often...according to this theory.

And, there is a counterargument as follows.

"There is completely no evidence, direct or indirect, to support this theory. Of course, some of the small pyramids built during the Middle and New Kingdoms were obviously designed to serve as tombs, and there are quite many in which mummies and coffins have been discovered. However, in the eight "Great" pyramids, which are believed to have been built during the 3rd and 4th Dynasties in the Old Kingdom, there is no evidence to show the existence of a coffin or mummy. These gigantic constructions are different in their structure from later tombs in every respect. The passageways are inclined so heavily that appear almost strange, and they are inconvenient for holding an Egyptian-style funeral service, known for its intricateness. The inside of the burial chamber is desolated, forming a conspicuous contraction with chambers seen in the later years that are decorated gorgeously with writings and engravings." (Reference 2)

In addition, here are doubts I have. According to the theory of Pharaoh's tomb, it is said that, after laying the Pharaoh's body in state in the King's Chamber, the group of burying workers left the room, operated a stone-throwing device in the antechamber to seal the King's Chamber, and then let the three granite blocks (each of them is about 1m wide, 1m high, and 2m long), which are now found at the low end of the ascending passageway, slide all the way down for about a few ten meters from the Great Gallery to block the way. But my questions are:

Question 1:
There are a lot of damages left on the wall of the Antechamber, signifying that there was some kind of intense movement there. These damages cannot be made only with a single movement of letting a carefully arranged stone slide down for once as the theory of Pharaoh's tomb argues.

Question2:
According to the measurements taken by Flinders Petrie, the width of the Great Gallery is narrower than the size of the granite blocks, and thereby the blocks cannot go through the Gallery. In short, it is impossible to transfer the stones used for blocking from the Great Gallery to the Ascending passageway.

Question3:
Moreover, here is another opinion. "It is said in the research done in Egypt by Davidson that the height and width of the granite stones blocking the low end of the Ascending passageway are clearly indicating that they have been placed when the pyramid reached its 17th steps. There is only 0.5 inch difference in width between the upper part of the Ascending passageway and the granite stones, and that is not enough for the stones to slide down through the Great Gallery. A conclusion has been reached to show that it would have been possible for the stone to get stuck at the halfway through in such a narrow space." (Reference 3)

After all
With these theories, the idea "the Great Pyramid is not a tomb for Pharaoh" is now spreading. And after all, the truth is "the purpose of the Great Pyramid is still unknown."

Reference
1. Secrets of the Great Pyramid (p236)
2. Serpent in the sky (p19) by John Anthony West, Shoei-sha 1997
3. Secrets of the Great Pyramid (p244)

Translated by Maiko Noda