PURPOSE: To effectively exclude the unauthorized opening of a pachinko board by outputting a signal to unlock a locking means when an ID code read in as a result of collation coincides with an ID code for collation.

CONSTITUTION: When a key 7 is inserted into a key hole 1 and turned in one direction, a CPU 15 judges to which side the key 7 is turned by a signal from a key insertion detection switch 11. When the key 7 is turned to, for example, the right side, the CPU 15 recognizes that a panel screen (glass screen) 2 is assumed as a target of unlocking, and generates a magnetic field from an antenna 5 via a transmission circuit 17, and reads in a key ID code from a transponder element 6 installed in the key 7. The CPU 15 reads out the ID code for collation from an EEPROM 16, and judges whether or not the key ID code of the transponder element 6 coincides with the ID code for collation. Consequently, when coincidence between the ID codes is obtained, a panel screen electromagnetic lock mechanism 12 is unlocked.