A stud pin installable in a tire, comprising: a tip comprising an end surface that comes into contact with a road surface; a body portion that supports the tip so that the tip projects from an end surface on one side of the body portion; and a lower flange connected to an end of the body portion on an opposite side to the end surface; a flange profile shape of the lower flange as viewed from an arrangement direction of the tip, the body portion, and the lower flange comprising an anisotropic shape in which, of imaginary rectangles circumscribing the flange profile shape, a first smallest rectangle with a shortest side of its four sides being smallest and/or a second smallest rectangle with a longest side of its four sides being smallest comprise short sides and long sides of different lengths; a body profile shape of the body portion as viewed from the arrangement direction having an anisotropic shape in which a length of the body profile shape in a longitudinal direction parallel with the long sides is different from a length of the body profile shape in a lateral direction parallel with the short sides; the body profile shape comprising four or more first body protrusion portions B1 projecting toward the lateral direction and two second body protrusion portions B2 projecting toward the longitudinal direction, characterized in that the flange profile shape comprises four first flange protrusion portions F1 projecting toward the longitudinal direction and two second flange protrusion portions F2 projecting toward the lateral direction, the first flange protrusion portions F1 are constituted by two pairs thereof; and the flange profile shape comprises two first flange recess portions F3 and four second flange recess portions F4, the two first flange recess portions F3 being curved toward a centroid of the flange profile shape and disposed between each of the pairs of the first flange protrusion portions F1, the four second flange recess portions F4 being curved toward the centroid, disposed between each of the second flange protrusion portions F2 and one of the first flange protrusion portions F1, and smoothly connect to one of the first flange protrusion portions F1. a tip comprising an end surface that comes into contact with a road surface; a body portion that supports the tip so that the tip projects from an end surface on one side of the body portion; and a lower flange connected to an end of the body portion on an opposite side to the end surface; a body profile shape of the body portion as viewed from the arrangement direction having an anisotropic shape in which a length of the body profile shape in a longitudinal direction parallel with the long sides is different from a length of the body profile shape in a lateral direction parallel with the short sides; the body profile shape comprising four or more first body protrusion portions B1 projecting toward the lateral direction and two second body protrusion portions B2 projecting toward the longitudinal direction, characterized in that the flange profile shape comprises four first flange protrusion portions F1 projecting toward the longitudinal direction and two second flange protrusion portions F2 projecting toward the lateral direction, the first flange protrusion portions F1 are constituted by two pairs thereof; and the flange profile shape comprises two first flange recess portions F3 and four second flange recess portions F4, the two first flange recess portions F3 being curved toward a centroid of the flange profile shape and disposed between each of the pairs of the first flange protrusion portions F1, the four second flange recess portions F4 being curved toward the centroid, disposed between each of the second flange protrusion portions F2 and one of the first flange protrusion portions F1, and smoothly connect to one of the first flange protrusion portions F1.