PURPOSE: To check a pin for defects without diassembling a machine, by forming an inspection hole for judgment in the longitudinal direction of the pin used as a fixing member for connection, and inspecting the deformation of the hole.

CONSTITUTION: An installation hole 3 is made in both a spindle 1 and a valve body 2 of, for example, a butterfly valve, and a taper pin 4 is inserted into this hole 3. In the longitudinal direction and at the central part of the taper 4, an inspection hole 5, which is straight, or free from any bend or warp, is formed, so that an inspection bar 6 can be inserted therein. When the inspection bar 6 can be inserted into the inspection hole 5 without compulsion, it is judged that the taper pin 4 is free from deformation or damage, or the pin 4 is normal. If shearing stress generated at the parts marked by 'A' of the taper pin 4 during its use results in deformation of or damage to the pin 4, the inspection bar 6 will not go into the inspection hole 5 because of the warp or bend of the inspection hole 5. Accordingly, the deformation of or damage to the pin 4 can be judged without diassembling the machine parts.