The volatile substance diffuser comprises a housing for a refill (1) containing the volatile substances that are diffused and a motion detector (2) that activates the diffuser upon detecting movement, and it also comprises a timer (3) that activates and/or deactivates a diffuser in accordance with predetermined time periods. The method comprises the stages of activating the volatile substance diffuser using the motion detector (2)； automatically deactivating the volatile substance diffuser after the first predetermined time period has elapsed； and maintaining the volatile substance diffuser deactivated for a second time period. It provides a diffuser and a method that prevents excessive battery wear and, at the same time, optimises the diffusion rate.
