PURPOSE: To easily attach and detach to and from a fixed part and fix to a fixed part at a clamp position, avoiding accidental disengagement from the fixed part.

CONSTITUTION: At least one pressurizing part 11 is supported in a casing 3. The pressurizing part 11 at least contacts fixed parts 1 and 2 by portions 98 and 99 at a clamping position. Pulling parts 12 and 13 are fixable to the pressurizing part 11 through a fixed part 1. Hooks 54 and 76 are so configured as to not displace relative to an insert opening 100 of the fixed part 1.