Abstract: To provide a device capable of firmly mounting a radio communication unit to a helmet in a simple manner without impairing the beauty and handleability of the helmet when the radio communication unit is detached from the helmet. The device for mounting a radio communication unit to a helmet includes a pair of couplers having a chucking function and a pair of magnetic connectors having a magnetically chucking function. The pair of magnetic connectors are provided with electrical contacts adapted to turn conductive when in a chucked condition. Furthermore, one of the pair of couplers and one of the pair of magnetic connectors is disposed on an outer surface of the helmet, while the other of the pair of couplers and the other of the pair of magnetic connectors is disposed on a main surface of the radio communication unit.