A security system wherein, when a staff enters a building, a smart card carried by the staff is verified, and staff information inclusive of a staff number and fingerprint information is read from the smart card and is stored temporarily in a temporary storage file. When the staff logs on to a terminal, the fingerprint of the staff is read by a fingerprint input device (LS) and verified with the fingerprint information of the temporary storage file for verification. When the staff leaves the building, the staff number is read from the smart card the staff carries, and the corresponding staff information is erased from the temporary storage file. Security of a security object inside a security zone can be improved.