The marker according to the present invention comprises: a first surface which includes a plurality of convex surfaces arranged at least in a first direction; and a second surface which is arranged inan upper-lower position with respect to the first surface, and which is projected on the plurality of convex surfaces as an optically detectable image. The second surface includes a plurality of first areas and a plurality of second areas that are optically mutually identifiable, wherein the interval between the centers of the plurality of first areas with respect to the first direction is greater than the interval between the apexes of the plurality of convex surfaces with respect to the first direction. The plurality of first areas are arranged farther from the convex surfaces than a focalposition of the plurality of convex surfaces. When external parallel light is made incident on the convex surfaces in an upper-lower direction, the width with respect to the first direction of a lightbundle formed by the convex surfaces at a height at which the first areas are arranged is not more than the width with respect to the first direction of the first areas.