To enable an input system for an electric lock to be installed on a door in addition to its mechanical lock without opening holes, notches, etc. to the utmost.

The structure of adding the input system for an electric lock besides an existing mechanical lock, which comprises a mechanical lock installed on a door and having at least a first hole to fit with a cylinder lock and a second hole to fit with an external handle, the door's external surface having a plurality of holes corresponding to the fitting holes for the mechanical lock, upper and lower insertion holes corresponding to the fitting holes for the mechanical lock and the holes for the door respectively, a storage casing for an input means formed in the way that it protrudes from the door front face, and an input plate additionally fixed to the external door surface via the cylinder lock fitted into the upper insertion holes and the external handle having its shaft fitted into the lower insertion holes.