A method for securely accessing a motor vehicle whose opening elements are locked and unlocked through wireless communication between a portable access device and an access control module on board the vehicle. The method includes authenticating the device with the access control module, unlocking the vehicle when the device has been authenticated, periodically transmitting, by way of the access control module, an interrogation signal into at least part of the passenger compartment of the vehicle intended for the device following unlocking of the vehicle, upon each reception by the device of said interrogation signal, triggering a first timeout the duration of which is greater than the transmission period of the interrogation signal, and deactivating the device when the first timeout has expired and the immobile state of the device is detected.