A portable device includes a main body, which has a mechanical key retainer, and a mechanical key, which is removably retained in the mechanical key retainer. An engagement projection extends from the mechanical key in a direction perpendicular to the direction in which the mechanical key is inserted into the mechanical key retainer. The engagement projection is formed from a resilient material. The mechanical key retainer includes an engagement recess for engaging the engagement projection when the mechanical key is retained in the mechanical key retainer. This structure reduces the size of the portable device and improves portability of the portable device.