A device for controlling access to at least one machine, the device comprising: - a portable object, which is separate from the machine, which is intended to be borne by a person and which comprises at least one first transmission member capable of transmitting via a wireless radio link a first signal, - a device for locking and unlocking of the machine, comprising: • a second wireless radio transceiver, capable of receiving the first signal, and • a third control member, which is connected to the second wireless radio transceiver and which is capable of causing an action of unlocking of the machine, - wherein the device for controlling access comprises a sixth means for calculation of a distance between the portable object and the device for locking and unlocking of the machine, connected to a seventh comparison means for comparison of the distance having been calculated to a prescribed value of distance (DMAX), characterized in that the third control member is capable of causing, when the second wireless radio transceiver has received the first signal, the transmission of a second signal by the second wireless radio transceiver to a fourth wireless radio receiver borne by the portable object, capable of receiving the second signal, the portable object comprises a fifth control member, which is connected to the first transmission member and to the fourth wireless radio receiver to cause, when the fourth wireless radio receiver has received the second signal, transmission of a third signal by the first transmission member to the second wireless radio transceiver, capable of receiving the third signal, the third control member and/or fifth control member being connected to the sixth means for calculation of a distance between the portable object and the device for locking and unlocking of the machine from the second and third signals (S2, S3) and/or from the first and second signals (S1, S2) and/or from the first and third signals (S1, S3), the portable object comprising an eighth member for autonomously supplying the first transmission member, the fourth wireless radio receiver and the fifth control member with power, the device for locking and unlocking of the machine comprising a ninth means for calculation of an angle of arrival (ANG1, ANG3) of the first signal and/or of the third signal and a tenth comparison means for comparison of the angle of arrival (ANG1, ANG3) having been calculated to at least one prescribed angular range, the seventh comparison means and the tenth comparison means being connected to the third control member to cause, when the tenth comparison means has determined that the angle of arrival (ANG1, ANG3) having been calculated is in the prescribed angular range and when the seventh comparison means has determined that the distance having been calculated is less than the prescribed value of distance (DMAX), the action of unlocking of the machine, and to cause, when the tenth comparison means has determined that the angle of arrival (ANG1, ANG3) having been calculated is not in the prescribed angular range and/or when the seventh comparison means has determined that the distance having been calculated is greater than the prescribed value of distance (DMAX), an action of locking of the machine. - a portable object, which is separate from the machine, which is intended to be borne by a person and which comprises at least one first transmission member capable of transmitting via a wireless radio link a first signal, - a device for locking and unlocking of the machine, comprising: • a second wireless radio transceiver, capable of receiving the first signal, and • a third control member, which is connected to the second wireless radio transceiver and which is capable of causing an action of unlocking of the machine, • a second wireless radio transceiver, capable of receiving the first signal, and • a third control member, which is connected to the second wireless radio transceiver and which is capable of causing an action of unlocking of the machine, - wherein the device for controlling access comprises a sixth means for calculation of a distance between the portable object and the device for locking and unlocking of the machine, connected to a seventh comparison means for comparison of the distance having been calculated to a prescribed value of distance (DMAX),