A portable key device for performing wireless communication with a control object device to release restriction on use, comprising: a first key device and a second key device that perform wireless communication with each other; a communication unit configured to perform wireless communication with another device; a biometric authentication context saving unit of the first key device configured to save a biometric authentication success context; and a detection unit of the first key device configured to detect wearing on a human body, wherein in a case where the detection unit is detecting the wearing of the first key device on the human body, the biometric authentication context saving unit receives and saves therein a biometric authentication success context, in a case where the biometric authentication context saving unit saves the biometric authentication success context and where a communication between the first key device and the second key device is established, the communication unit of the second key device emits a release signal that makes the restriction on use of the control object device be released, in a case where the biometric authentication context saving unit saves the biometric authentication success context and where a communication between the first key device and the second key device is interrupted, the biometric authentication success saving unit still saves the biometric authentication success context and the communication unit of the second key device stops emission of the release signal, and when the detection unit detects removal of the first key device from the human body by detecting a shape change caused by the wearing on the human body, the biometric authentication context saving unit discards the biometric authentication success context and the communication unit of the second key device stops emission of the release signal. a first key device and a second key device that perform wireless communication with each other; a communication unit configured to perform wireless communication with another device; a biometric authentication context saving unit of the first key device configured to save a biometric authentication success context; and a detection unit of the first key device configured to detect wearing on a human body, wherein in a case where the detection unit is detecting the wearing of the first key device on the human body, the biometric authentication context saving unit receives and saves therein a biometric authentication success context, in a case where the biometric authentication context saving unit saves the biometric authentication success context and where a communication between the first key device and the second key device is established, the communication unit of the second key device emits a release signal that makes the restriction on use of the control object device be released, in a case where the biometric authentication context saving unit saves the biometric authentication success context and where a communication between the first key device and the second key device is interrupted, the biometric authentication success saving unit still saves the biometric authentication success context and the communication unit of the second key device stops emission of the release signal, and when the detection unit detects removal of the first key device from the human body by detecting a shape change caused by the wearing on the human body, the biometric authentication context saving unit discards the biometric authentication success context and the communication unit of the second key device stops emission of the release signal. <EOS>