A vehicular electronic key system (10; 11) comprising: an electronic key (100; 101) and a wireless communication device (200; 201), wherein the electronic key (100; 101) including a first communication unit configured to perform wireless communication with a vehicle, a second communication unit configured to perform wireless communication with the wireless communication device (200; 201), and a first controller configured to switch an operating state between an ON state where a function of the first communication unit is operated, and an OFF state where the function of the first communication unit is at least partially stopped, based on a result of communication of the second communication unit with the wireless communication device (200; 201); and the wireless communication device (200; 201) including a third communication unit configured to perform wireless communication with the second communication unit, and a second controller configured to cause the third communication unit to transmit a predetermined signal, wherein the first controller is configured to switch the operating state from the ON state to the OFF state when the first controller detects that the electronic key (100; 101) has been moved by a predetermined distance or longer outside the vehicle based on at least a result of communication of the predetermined signal by the second communication unit. the electronic key (100; 101) including a first communication unit configured to perform wireless communication with a vehicle, a second communication unit configured to perform wireless communication with the wireless communication device (200; 201), and a first controller configured to switch an operating state between an ON state where a function of the first communication unit is operated, and an OFF state where the function of the first communication unit is at least partially stopped, based on a result of communication of the second communication unit with the wireless communication device (200; 201); and a first communication unit configured to perform wireless communication with a vehicle, a second communication unit configured to perform wireless communication with the wireless communication device (200; 201), and a first controller configured to switch an operating state between an ON state where a function of the first communication unit is operated, and an OFF state where the function of the first communication unit is at least partially stopped, based on a result of communication of the second communication unit with the wireless communication device (200; 201); and the wireless communication device (200; 201) including a third communication unit configured to perform wireless communication with the second communication unit, and a second controller configured to cause the third communication unit to transmit a predetermined signal, a third communication unit configured to perform wireless communication with the second communication unit, and a second controller configured to cause the third communication unit to transmit a predetermined signal, wherein the first controller is configured to switch the operating state from the ON state to the OFF state when the first controller detects that the electronic key (100; 101) has been moved by a predetermined distance or longer outside the vehicle based on at least a result of communication of the predetermined signal by the second communication unit.