To provide a push button lock which includes a housing on which a plurality of depressible push buttons are located, a lock pin which moves axially with the push button and being engageable with and disengageable from the push button, a lock plate formed with a plate key hole and plate lock hole, a reset plate which is provided parallel to the lock plate, a driving cam linked to a deadbolt lock, and the security-code controller detachably attached to the housing. A mechanism and components for setting and storing a security code for locking and unlocking are assembled in a cartridge. The cartridge is detachably attached to the inside of the housing so that various surface designs are available.