A diffuser may include a diffusing case having a rear side removably coupled to a main body of a hair dryer. Fluid (such as gas or air) discharged from the main body is introduced into the diffusing case through an inlet hole defined at the rear side. The fluid introduced into the diffusing case is discharged to an outside through a front side of the diffusing case. A light irradiator may be provided inside the diffusing case to irradiate light toward the front side of the diffusing case. The light irradiator may include a plurality of light emitters arranged on a circuit board to emit light. Some of the plurality of light emitters may be spaced apart from others of the plurality of light emitters in a front-rear direction.