A size measuring device which, when attached to a user, specifies a size and shape of an attached body portion of the user, comprising: a main body part constituted by an expandable material; measuring sensors (Sc1 to Sc13) for measuring a physical numeric value based upon a change in an electrical characteristic, wherein the measuring sensors (Sc1 to Sc13) measure a degree of expansion of a base member caused by the shape of a user's body, and the measuring sensors (Sc1 to Sc13) are disposed on the main body part in a polygonal pattern, characterized in that plural measuring sensors (Sc1 to Sc13) are disposed in a triangular polygonal shape in which a plurality of triangles are adjacent to one another on the main body part, wherein the respective measuring sensors (Sc1 to Sc13) form one of sides of each triangle, and mutually adjacent sides of the triangles share one measuring sensor (Sc1 to Sc13), wherein the respective nodes (Nd1 to Nd4) are shared by six sensors, wherein each measuring sensor (Sc1 to Sc13) has a belt shape, and nodes (Nd1 to Nd4) corresponding to two ends in a belt length direction are shared among the plural measuring sensors (Sc1 to Sc13) adjacent to each other, and wherein the measuring sensors (Sc1 to Sc13) are either (i) measuring sensors (Sc1 to Sc13) having a pair of plate-shaped electrodes (1202, 1203) and a dielectric film disposed between the paired electrodes (1202, 1203), wherein when a tension is applied to the electrodes (1202, 1203) so as to be expanded, the measuring sensors specify the degree of expansion of the electrodes (1202, 1203) caused by the shape of a user's body based upon a change in electrostatic capacitance caused by the expansion of the electrodes (1202, 1203); or (ii) measuring sensors (Sc1 to Sc13) having plate-shaped electrodes (1202, 1203) having expandability, and when a tension is applied to the electrodes (1202, 1203) so as to be expanded, the measuring sensors (Sc1 to Sc13) specify the degree of expansion of the electrodes (1202, 1203) caused by the shape of a user's body based upon a change in electric resistance value caused by the expansion of the electrodes (1202, 1203). a main body part constituted by an expandable material; measuring sensors (Sc1 to Sc13) for measuring a physical numeric value based upon a change in an electrical characteristic, wherein the measuring sensors (Sc1 to Sc13) measure a degree of expansion of a base member caused by the shape of a user's body, and the measuring sensors (Sc1 to Sc13) are disposed on the main body part in a polygonal pattern, characterized in that plural measuring sensors (Sc1 to Sc13) are disposed in a triangular polygonal shape in which a plurality of triangles are adjacent to one another on the main body part, wherein the respective measuring sensors (Sc1 to Sc13) form one of sides of each triangle, and mutually adjacent sides of the triangles share one measuring sensor (Sc1 to Sc13), wherein the respective nodes (Nd1 to Nd4) are shared by six sensors, wherein each measuring sensor (Sc1 to Sc13) has a belt shape, and nodes (Nd1 to Nd4) corresponding to two ends in a belt length direction are shared among the plural measuring sensors (Sc1 to Sc13) adjacent to each other, and wherein the measuring sensors (Sc1 to Sc13) are either (i) measuring sensors (Sc1 to Sc13) having a pair of plate-shaped electrodes (1202, 1203) and a dielectric film disposed between the paired electrodes (1202, 1203), wherein when a tension is applied to the electrodes (1202, 1203) so as to be expanded, the measuring sensors specify the degree of expansion of the electrodes (1202, 1203) caused by the shape of a user's body based upon a change in electrostatic capacitance caused by the expansion of the electrodes (1202, 1203); or (ii) measuring sensors (Sc1 to Sc13) having plate-shaped electrodes (1202, 1203) having expandability, and when a tension is applied to the electrodes (1202, 1203) so as to be expanded, the measuring sensors (Sc1 to Sc13) specify the degree of expansion of the electrodes (1202, 1203) caused by the shape of a user's body based upon a change in electric resistance value caused by the expansion of the electrodes (1202, 1203).