An optical scale (11; 11a; 11A; 11B; 111; 11J; 11AT; 11BT; 11CT; 11DT; 11ET; 11FT; 11GT; 11HT; 11HW; 11HX; 11HY; 11HZ; 11Y4; 11Y5; 11Y8; 11Y11; 11Y12) through or on which light source light (71; 71AT; 71BT) from a light source (41; 41AT; 41BT) is passed or reflected, the optical scale (11; 11a; 11A; 11B; 111; 11J; 11AT; 11BT; 11CT; 11DT; 11ET; 11FT; 11GT; 11HT; 11HW; 11HX; 11HY; 11HZ; 11Y4; 11Y5; 11Y8; 11Y11; 11Y12) comprising: a plurality of wires (g; g1; g2; g3; g4) arranged thereon so that the plurality of wires (g; g1; g2; g3; g4) do not intersect each other and each of tangential directions of the wires (g; g1; g2; g3; g4) changes continuously while the optical scale (11; 11a; 11A; 11B; 111; 11J; 11AT; 11BT; 11CT; 11DT; 11ET; 11FT; 11GT; 11HT; 11HW; 11HX; 11HY; 11HZ; 11Y4; 11Y5; 11Y8; 11Y11; 11Y12) is rotated once; characterized by: a transmissive area (w) provided between each of two adjacent wires (g), through which the entire or a part of light is allowed to pass; wherein the plurality of wires (g; g1; g2; g3; g4) forms a line pattern; wherein a tangential angle θd is cyclically changed, correspondingly to a rotation angle θrot if the optical scale (11; 11a; 11A; 11B; 111; 11J; 11AT; 11BT; 11CT; 11DT; 11ET; 11FT; 11GT; 11HT; 11HW; 11HX; 11HY; 11HZ; 11Y4; 11Y5; 11Y8; 11Y11; 11Y12) is rotated once; wherein a width (Δw1) of a transmissive area (w) between two wires (g1, g2) at a position of a first radial direction is different from a width (Δw2) of the transmissive area (w) between the two wires (g1, g2) at a position of a second radial direction. a plurality of wires (g; g1; g2; g3; g4) arranged thereon so that the plurality of wires (g; g1; g2; g3; g4) do not intersect each other and each of tangential directions of the wires (g; g1; g2; g3; g4) changes continuously while the optical scale (11; 11a; 11A; 11B; 111; 11J; 11AT; 11BT; 11CT; 11DT; 11ET; 11FT; 11GT; 11HT; 11HW; 11HX; 11HY; 11HZ; 11Y4; 11Y5; 11Y8; 11Y11; 11Y12) is rotated once; characterized by: a transmissive area (w) provided between each of two adjacent wires (g), through which the entire or a part of light is allowed to pass; wherein the plurality of wires (g; g1; g2; g3; g4) forms a line pattern; wherein a tangential angle θd is cyclically changed, correspondingly to a rotation angle θrot if the optical scale (11; 11a; 11A; 11B; 111; 11J; 11AT; 11BT; 11CT; 11DT; 11ET; 11FT; 11GT; 11HT; 11HW; 11HX; 11HY; 11HZ; 11Y4; 11Y5; 11Y8; 11Y11; 11Y12) is rotated once; wherein a width (Δw1) of a transmissive area (w) between two wires (g1, g2) at a position of a first radial direction is different from a width (Δw2) of the transmissive area (w) between the two wires (g1, g2) at a position of a second radial direction. a transmissive area (w) provided between each of two adjacent wires (g), through which the entire or a part of light is allowed to pass; wherein the plurality of wires (g; g1; g2; g3; g4) forms a line pattern; wherein a tangential angle θd is cyclically changed, correspondingly to a rotation angle θrot if the optical scale (11; 11a; 11A; 11B; 111; 11J; 11AT; 11BT; 11CT; 11DT; 11ET; 11FT; 11GT; 11HT; 11HW; 11HX; 11HY; 11HZ; 11Y4; 11Y5; 11Y8; 11Y11; 11Y12) is rotated once; wherein a width (Δw1) of a transmissive area (w) between two wires (g1, g2) at a position of a first radial direction is different from a width (Δw2) of the transmissive area (w) between the two wires (g1, g2) at a position of a second radial direction.