A plant sensor includes a first light emitter to emit first measuring light with a first wavelength to irradiate a growing condition measurement target therewith; a second light emitter to emit second measuring light with a second wavelength to irradiate the growing condition measurement target therewith; a light receiver to receive reflected light of each of the first and second measuring light from the growing condition measurement target and output a received light signal; a controller to control light emission; a light path merging unit to merge a first outgoing light path of the first measuring light from the first light emitter and a second outgoing light path of the second measuring light from the second light emitter; and a common outgoing light path connecting the light path merging unit to a light exit portion emitting the first measuring light and the second measuring light.