Colorimeter includes an illumination light reception unit, an attached part, a detection unit, a recognition unit, a color measurement control unit, and an output unit. To the attached part, a mask member is attached to cover the illumination light reception unit. The detection unit detects parts disposed on the mask member. The recognition unit recognizes information on the kind of the mask member in accordance with a detection result by the detection unit. The color measurement control unit causes the recognition unit to recognize information on the kind of mask member in accordance with the detection result at a first timing, and on the kind of mask member in accordance with the detection result at a second timing. The output unit performs a predetermined output in response to a discordance between the information on the kind of mask member at the first timing and at the second timing.