The present invention relates to a device and a method for measuring skin changes caused by blue light. A device for measuring skin changes caused by blue light according to one embodiment of the present invention comprises: at least one light source for irradiating light of a blue light band at different light amounts to a plurality of test areas set on a skin area to be tested; and a control unit for detecting a minimum pigmentation point among the test areas and calculating a light amount of the corresponding test area as a minimum pigmentation dose (MPD) for blue light. In addition, the present invention relates to a blue light irradiation device for irradiating a plurality of blue light beams in order to measure skin changes caused by blue light.