A communication device includes a plurality of key distributing units, a plurality of communicating units, a monitoring unit, and a switching unit. The plurality of key distributing units have a quantum key distribution function for sharing a quantum key with an external distribution device. The plurality of communicating units communicate with an external communication device using the quantum key. The monitoring unit monitors operational status indicating at least one of transmission-reception status of photons in the quantum key distribution function, generation status of generating the quantum key, and obtaining status of obtaining the quantum key. The switching unit switches a control target, which either represents one of the key distributing units or represents one of the communicating units, from a first control target to a second control target other than the first control target according to the operational status.