To provide a code uneven key capable of securing sufficient locking strength by a pintumbler in both a case for not inserting a key when a code uneven key is not inserted into a key hole and a case for inserting an unauthentic key when a plate material is inserted into the key hole as the unauthentic key.

A card key 42 formed of a card such as a credit card in which a key code is formed is used as the emergency key of the electronic key system of a vehicle. Since the card key 42 is positioned as the emergency key, it is a key which requires mechanical operation (real operation action) during key operation. A hole formation pattern 45 consisting of a hole 46 including group and a hole 46-free group is formed at the card and is used as a key code for a mechanical key. The number ratio of holes 46 to hole-free parts 47 is set to allow one to take 50% and 60% of total hole including and hole-free groups.