To provide a lock device of a passage opening-closing handle for constituting a stopper of one member, reducing the number of part items, and easy in installation to a fluid controller.

A stopper support 12 has a square plate-like part 15 having a circular through-hole 16 fitted to a cylindrical part 7 of a fluid controller body 2, a lower projecting part 17 arranged in a lengthwise directional one end part of the square plate-like part 15 and applied to one side surface of a rectangular solid part 4 of the fluid controller body 2 and an overhang part 15a overhanging outside from the rectangular solid part 4 among the square plate-like part 15. A stopper 13 formed in a vertical plate shape is vertically movably inserted into a through-hole 18 arranged in the overhang part 15a of the stopper support 12. The stopper 13 has an abutting part 19 for externally abutting from the width direction on a grip part 3a of the handle 3 in a lock position and a lock installing part 20 existing above the stopper support 12 in the lock position.