In order to provide a lancet which has a simple structure and which can secure safety, in particular, after use, and a lancet device including the same, a lancet (20) includes a casing (22), and a puncture body (23) which is accommodated in the casing (22) so as to be movable in a puncturing direction. For removing the lancet (20) from a main body (30), the lancet (20) has a convex portion (22b) formed on an inner surface (22a) of the casing (22) and a recessed portion (groove (23c)) formed on the puncture body (23), which form fitting for holding the puncture body (23) so as to be immovable in the puncturing direction in the casing (22).
