Obtained is a controller for an air-conditioning apparatus with which indication by light can be effectively performed. The controller includes a light source 21 capable of emitting light in a plurality of colors and a light guiding member 22 that diffuses the light emitted from the light source 21 so as to increase an indication area, thereby performing light indication in an indication region 22a. By increasing the light indication area, light indication can be effectively performed, and accordingly, visual recognition by the user can be easily performed.