To provide a drilling assisting tool of an electric drill with which accurate drilling operation can be executed promptly and easily.

An electric drill 50, which is mounted on a mounting member 10 while a contact member 20 is in contact with a surface to be drilled, moves along guide members 30, whereby the electric drill can drill the surface to be drilled with a drilling assisting tool 1 through a through-hole 22. The contact member 20 includes a first strip part 24 and a second strip part 26, which are orthogonal to each other on a plane where the contacting surface between the surface to be drilled is perpendicular to the guide members 30, and the through-hole 22 is formed in an intersection of the first strip part 24 and the second strip part 26.