Abstract: A magnetic sensor disposed in an opposing relation to a magnetic scale magnetized at a grating pitch .lambda. in the length direction thereof and which is movable relative to the magnetic scale in the length direction is comprised of at least two magnetoeffect resistance elements disposed with a distance of (.lambda./2).multidot.n (n=1, 2, 3, . . . ) in the length direction, the two magnetoeffect resistance elements being formed in the width direction perpendicular to the length direction and each of the magnetoeffect resistance elements having partial magnetoeffect resistance elements distant from each other by a distance of (.lambda./2).multidot.(1/2m) (m=2, 3, 4, . . . ) from a predetermined position on the width direction perpendicular to the length direction, wherein the two magnetoeffect resistance elements are shaped as substantially symmetrical configurations relative to a central line in the length direction.