A method for easily and quickly evaluating the wavelength variability properties of a wavelength-variable semiconductor laser is provided. An inspection device includes a power source for supplying current to a wavelength-variable DBR semiconductor laser having an active region, a phase control region, and a DBR region, a photo-detector for detecting an output intensity of laser beam emitted from the wavelength-variable DBR semiconductor laser, and a transmission type wavelength-selection element that can be inserted into a light path from the wavelength-variable DBR semiconductor laser to the photo-detector. In a state where the transmission type wavelength-selection element is inserted into the light path from the wavelength-variable DBR semiconductor laser to the photo-detector, at least one of a phase current that is supplied to the phase control region and a DBR current that is supplied to the DBR region is changed with respect to a predetermined active current that is supplied to the active region, and the output intensity of the laser beam after the laser beam has passed through the transmission type wavelength-selection element is detected by the photo-detector.