Electronic key structure

An electronic key structure for electronic keys in which a key body is formed with a mechanical key storing part for at least a key plate part of a mechanical key to be stored therein, and the mechanical key is insertable into and removable from the mechanical key storing part, wherein the mechanical key storing part is located at one side of the key body, an aperture thereof is formed at a rear end surface of the key body, a key head of the mechanical key is formed with a bulge bulging at one lateral side to the one side, and a bridging piece for a holder linking hole to be formed therein is provided at a rear edge of the key head, in position to protrude at the opposite side of the key body, on the rear end surface of the key body, in a mechanical key storing condition, wherein the key body comprises an upper cover and a lower cover, the upper and lower covers being formed by splitting the key body in two pieces in a thickness direction, the upper cover and lower cover being mated and held together, and the mechanical key storing part being provided so as to be offset toward one of the covers.