To provide a tool for assembling a torque limiter that can reduce the number of work steps in an assembling operation.

The assembling tool 100 includes, in an order from a radial inside of the rotation axis thereof: a phase matching part 110 relatively moving in an axial line direction of the rotation axis toward friction members 5 while engagement plates 4, the friction members 5 and a disc spring 9 are disposed in a drum 2 of a torque limiter 1 to match phases of internal splines 11a, 11b provided at inner peripheries of the friction members 5; a pressing part 120 relatively moving in the axial line direction toward the engagement plates 4 to apply a pressing load against the pressure of the disc spring 9 in the axial line direction relative to the engagement plates 4, the friction members 5 and the disc spring 9 that are disposed in the drum 2; and a mounting part 130 relatively moving in the axial line direction toward the drum 2 while coming into contact with a snap ring 10 to mount the snap ring 10 in the drum 2.