To provide a sensitivity distribution measuring method and apparatus for a photosensor capable of grasping a sensitivity characteristic of the photosensor in detail.

This sensitivity distribution measuring apparatus 2 is provided with an inspection plate 11 with an inspection face 11a drawn with an eccentric circle 20 having a black line 22 and a black-painted area 23, a sensor holder 12 for holding the photosensor 10 and the inspection plate 11 to face an arranging face 10c arranged with a light emitting element 10a and a light receiving element 10b to the inspection face 11a, an inspection plate holder 13, the first stepping motor 14 for rotating the arranging face 10c with respect to the inspection face 11a, the second stepping motor 15 for rotating the inspection plate 11 at a constant speed, and a host computer 16 for drawing out a sensitivity distribution D2 expressed two-dimensionally, based on an output signal from the light receiving element 10b in every of rotations, by driving the first stepping motor 14 to rotate the arranging face 10c at plurality of times and by driving the second stepping motor 15 in the every of the rotations, and for composing the plurality of obtained sensitivity distributions D2 to draw out a sensitivity distribution D3 expressed three-dimensionally.