To provide a jig for assembling a coil spring by which a compression coil spring can be surely assembled even in a hydraulic motor with brake whose motor cover is thin.

The jig for assembling a coil spring is equipped with a spring retaining plate having a recess for retaining a spring at one end, a motor cover gripping plate, a coupling means for coupling the other end of the spring retaining plate to the other end of the motor cover gripping plate and a clearance holding means for holding the spring retaining plate and the motor cover gripping plate with a prescribed space in between.