The present disclosure relates to a smart mirror, a controlling method thereof, and a system for purchasing a cosmetic. According to an aspect of the present disclosure, a smart mirror comprising: a terminal unit including a sensor capable of recognizing a user; a lighting unit including an LED capable of irradiating light to the user; and a control module capable of controlling at least one of the amount of light and the color temperature of the light irradiated from the lighting unit so that the skin of the user represents the light amount and the color temperature in a preset range by the light irradiated from the lighting unit may be provided.