To provide a jig for step mounting holes, which jig can simply and easily position multi stage step mounting holes, and further can surely guide a drill at a required position.

The jig for the step mounting holes comprises a scale body 1 composed of upper and lower horizontal portions 2, 3 and a vertical portion 4 for connecting the middle portions of the respective horizontal portions in the vertical direction, drill passing elongated holes 5 formed in the neighborhood of both ends of the respective horizontal portions of the scale body, a connecting recessed portion 7 or a connecting convex portion 9 formed on the vertical portion at the respective projecting ends of projecting portions 6, 8 vertically projecting from the horizontal portions, levels 10 arranged in the neighborhood of the crossing portions of the vertical portion 4 with the horizontal portions, a grip 11 fixed to the vertical portion between both horizontal portions, threaded holes 12 formed at the central portions of the respective horizontal portions. Thus, the jig for the step mounting holes is composed of the scale body, drill guide blocks 15 to be slidably engaged with the respective elongated holes of the horizontal portions, adjust screws 16 which are arranged between a wall surface and the scale body, and are screwed into the threaded holes.