To provide a constant pressure stimulation apparatus having a function of locally pressing the skin with a constant pressure to search for a trigger point of pain.

The constant pressure stimulation apparatus has a light emitting device 108 for emitting light; a projecting part 104 abutting on the skin 2 of a living body to search for the trigger point of pain, which is an indurated region to be irradiated with the light; and a pressure measuring part 110 to measure the pressure applied to the living body by the projecting part 104. The projecting part 104 is moved forward/backward by a driving part 112 to adjust the pressure so that the measured pressure is equivalent to a preset pressure.