To provide a fitting coupler of a sprinkler head enabling easy fitting/ removing of a sprinkler head to piping and preventing persons not concerned from removing the sprinkler head.

In a structure of the fitting coupler of the sprinkler head, one or more engaging materials 30 engaging with the sprinkler head are installed in an outer cylinder 20 for enabling engaging and releasing of the sprinkler head. The engaging and releasing of the sprinkler head is performed by rotating the outer cylinder 20. Alternatively, an engaging means of the sprinkler head is formed so as to engage the sprinkler head by pressing an engaging material 60 toward the center of the fitting coupler of the sprinkler head, and a releasing means is formed so as to release the engaging by inserting a bar into a releasing part 63 provided on a divided part 61 of the engaging material.