Guinea Pig: Devil's Experiment (Japanese: ギニーピッグ 悪魔の実験, Hepburn: Ginī Piggu: Akuma no Jikken) is a 1985 Japanese exploitation horror film written and directed by Satoru Ogura, and the first film in the Guinea Pig film series.

The film depicts a group of three men who graphically abuse a woman in a number of ways. It is presented in a found-footage style, with on-screen text claiming that the film features real footage of torture—supposedly intended as an experiment on the human body's tolerance to pain—that was purportedly sent to Ogura. However, the scenes of violence featured in the film are not authentic, extensively utilising practical effects.

Guinea Pig: Devil's Experiment has been called a "faux snuff film", and has been noted for its depiction of violence.