According to one embodiment of the present disclosure, a device for diagnosing a pigmented lesion includes: a sound detector configured to detect a photoacoustic wave generated when a laser is irradiated onto a target from which a pigmented lesion is to be identified and a diagnosis unit configured to calculate a depth and/or thickness of the pigmented lesion, based on a time at which the photoacoustic wave is detected, and laser irradiation time information on the laser irradiated onto the target.
