A security device and a security system are provided. The security system includes the security device. The security device includes a first I/O module and a processing unit. The first I/O module is configured to detect an identification within a detection coverage. The processing unit is configured to: determine that the identification is registered with the security device; set the security device as an unalarmed mode when the identification is enabled within the detection coverage of the first I/O module; and set the security device as an alarmed mode when the identification is disabled within the detection coverage of the first I/O module.