To improve operability in code conversion, and to secure safety.

In a code-variable cylinder lock, a front opening 11a of an outer cylinder comprises: a locking-position opening edge 11A which is concavely formed on a radial outside; a conversion-position opening edge 11B which is concavely formed on the radial outside; a first rotational edge 11C which is elongated along a rotational direction between the locking-position opening edge and the conversion-position opening one; and a second rotational edge 11D which is elongated along the rotational direction opposite to the side of the first rotational edge 11C from the conversion-position opening edge. An opening range in at least one of the radial and rotational directions of the locking-position opening edge is set wider than an opening range in at least one direction of the conversion-position opening edge. The first rotational edge is positioned on the radial outside with respect to the second rotational edge.