A time-domain pulsed spectroscopy apparatus which has a pulsed laser light source; a splitting unit to split pulsed laser light; a pulsed-light emitting unit; a detector; a sample holder; and a sample-unit entrance and exit optical systems; wherein the time-domain pulsed spectroscopy apparatus further comprises: at least one optical-path-length varying unit for setting a photometric range; at least one optical delay unit for the wave form signal measurement; and, at least one gate member to pass or block the pulsed light to a reflector.