To provide a mechanism capable of discriminating the number of use of a reusable or disposal device and displaying when the device is no more effective or safe for use.

This counter mechanism 1 discriminates durability service life of the reusable or disposal device. It includes an actuator 15 for driving a counter 14 every time when the device 2 is used and sterilized and/or two parts or more of the device 2 are fitted. A display device 30 may be provided to display the number of drive of the counter 14. Moreover, a signal device may be provided to display that the device must not be used any more in accordance with specific number of use of the device (based on actual number of use and sterilization and/or fitting of two parts or more). Furthermore, an impossible mechanism 40 may be provided to prevent further use of the device after the specific number of use.