A communication device comprising: a detector configured to detect an optical signal from another communication device and convert the optical signal to an electric signal; a data processing unit configured to process the electric signal converted by the detector to acquire data; and characterized in further comprising a controller configured to control, on a basis of the optical signal detected by the detector, an operating state including a standby state in which the data processing unit is deactivated to reduce power consumption and an active state in which the data processing unit is capable of executing acquisition of the data, wherein the detector is configured to detect the optical signal in the standby state; the detector is further configured to perform an intermittent operation capable of detecting the optical signal at least every predetermined period of time in the standby state; the detector is further configured to detect an optical signal in the active state; the controller is configured to determine whether the optical signal is an standby transition request signal for requesting the communication device to transition to the standby state on a basis of an average power of the optical signal detected by the detector in the active state, and in a case where the optical signal is determined to be the standby transition request signal, the controller is configured to cause the communication device to transition from the active state to the standby state; and in a case where the optical signal detected by the detector in the active state is an optical signal having an average power less than a predetermined optical power, which continues for a predetermined time or longer, the controller is configured to determine that the optical signal is the standby transition request signal. a detector configured to detect an optical signal from another communication device and convert the optical signal to an electric signal; a data processing unit configured to process the electric signal converted by the detector to acquire data; and characterized in further comprising a controller configured to control, on a basis of the optical signal detected by the detector, an operating state including a standby state in which the data processing unit is deactivated to reduce power consumption and an active state in which the data processing unit is capable of executing acquisition of the data, wherein the detector is configured to detect the optical signal in the standby state; the detector is further configured to perform an intermittent operation capable of detecting the optical signal at least every predetermined period of time in the standby state; the detector is further configured to detect an optical signal in the active state; the controller is configured to determine whether the optical signal is an standby transition request signal for requesting the communication device to transition to the standby state on a basis of an average power of the optical signal detected by the detector in the active state, and in a case where the optical signal is determined to be the standby transition request signal, the controller is configured to cause the communication device to transition from the active state to the standby state; and in a case where the optical signal detected by the detector in the active state is an optical signal having an average power less than a predetermined optical power, which continues for a predetermined time or longer, the controller is configured to determine that the optical signal is the standby transition request signal. <EOS>