To facilitate the work for fitting an operation part 6 and the work for adjusting the projection length in a socket removing mechanism formed of a support shaft 11 to be fitted on a base end part of a plug part 21 of a gas plug main body 2 in the condition that the support shaft can not turn, a rock lever 12 rocking around the support shaft and provided with pushing pieces 12a and 12b for pushing a tip surface of a socket in a releasing direction and the operation part 6 continuously provided to the other end of the rock lever to operate the rock lever 12.

The gas plug main body 2 is integrally provided with a fixed plate 4, and the operation part 6 is formed of a shaft body 63 locked with the fixed plate 4 through the rock lever 12 to prevent a fall thereof, a male screw cylinder part 64 fitted on the shaft body freely to move forward and backward, preventing a fall thereof, and provided with an energizing means 66 for pushing the rock lever 4 toward the fixed plate 4 side, and a cap part 65 provided with a female screw cylinder part to be screwed onto the male screw cylinder part.