The present invention aims to provide an optical pressure sensor capable of detecting a more minute pressure change. A base film is formed with a through hole passing first and second surfaces, an optical fiber is fixed to the base film at a region other than the FBG portion such that the FBG portion is positioned on the through hole in plan view. The optical pressure sensor according to the present invention is attached to an object body such that the second surface of the base film is closely attached to a surface of the object body directly or indirectly.