A humidifier includes a case; a humidifying device which is disposed inside the case and generates humidified air; a light source which is disposed inside the case, and emits light; and a light diffuser which diffuses the light emitted from the light source, wherein the case includes: a peripheral wall; and a discharge flow path which extends in an up-down direction from an inner side of the peripheral wall, and is located in an upper side of the humidifying device, wherein in the peripheral wall, at least a portion corresponding to a vertical location of the discharge flow path is transparent, wherein the light source is disposed in a lower side of the discharge flow path, and wherein the light diffuser is disposed between the light source and the discharge flow path and extends downward in a center direction of the case.