A dermatological treatment device using a light beam, includes: a laser source (1) suitable for directing a laser beam onto at least one zone (2) of the area of skin to be treated, a contactless measurement unit sensitive to radiation according to temperature, of the temperature of a skin area corresponding to the area of skin being treated, and a unit for controlling (13) the laser source via the measurement unit, the device being characterised by the fact that the contactless measurement unit includes an infrared sensor (4) and an objective lens (20) suitable for focusing the field of view (5) of the infrared sensor such that the area of skin contained within the field of view (5) is fully included in the area of skin (2) being treated by the device.
