A magnetized scale (1a) in which magnetic pole pairs each formed of a first magnetic portion (11a) and a second magnetic portion (12a) having different magnetic properties are arranged with a period of a magnetic pole pair width 2λ, and a magnetosensitive device (2) in which n magnetosensitive elements (21a to 21e) are arranged with a magnetosensitive element pitch P so that λ=nP may be established are arranged so as to be opposed to each other with a predetermined air gap therebetween. Output values output from the n magnetosensitive elements (21a to 21e) in parallel are analyzed to calculate a relative position between the magnetosensitive device (2) and the magnetized scale (1a) as a position detection resolution of λ/n.