Optical position measuring device, having two scales, for detecting the relative position of these two scales (M1, M2; 10, 20; 110, 120; 210, 220; 310, 320), which can be moved relative to one another along a plurality of measuring directions (x, y, z) and which are arranged in different planes and are crossed relative to each other, wherein - the two scales (M1, M2; 10, 20; 110, 120; 210, 220; 310, 320) each have a measuring graduation (11, 21; 111, 121) with periodically arranged grating regions (11a, 11b, 21a, 21b; 111a, 111b, 121a, 121b) with different optical properties, and the directions of longitudinal extent of the scales (M1, M2; 10, 20; 110, 120; 210, 220; 310, 320) are oriented parallel to a first and second measuring direction (x, y), wherein a horizontal movement plane is spanned by the first and second measuring direction (x, y) and a third measuring direction (z) is oriented at right angles to the first and second measuring direction (x, y), and - on the first scale (M2; 20; 120; 220; 320), an illumination beam emitted by a light source (31.1) is split into at least two partial beams, and - the partial beams subsequently strike the second scale (M1; 10; 110; 210; 310), which is arranged to be tilted with respect to the horizontal movement plane about the direction of its longitudinal extent, wherein the partial beams experience back-reflection on the second scale (M1; 10; 110; 210; 310) in the direction of the first scale (M2; 20; 120; 220; 320), and - the back-reflected partial beams strike the first scale (M2; 20; 120; 220; 320) again and are recombined there, so that a resultant signal beam is then propagated in the direction of a detection unit, via which a plurality of phase-shifted scanning signals with respect to the relative movement of the scales (M1, M2; 10, 20; 110, 120; 210, 220; 310, 320) along the third measuring direction (z) and the first or second measuring direction (x, y) can be generated. - the two scales (M1, M2; 10, 20; 110, 120; 210, 220; 310, 320) each have a measuring graduation (11, 21; 111, 121) with periodically arranged grating regions (11a, 11b, 21a, 21b; 111a, 111b, 121a, 121b) with different optical properties, and the directions of longitudinal extent of the scales (M1, M2; 10, 20; 110, 120; 210, 220; 310, 320) are oriented parallel to a first and second measuring direction (x, y), wherein a horizontal movement plane is spanned by the first and second measuring direction (x, y) and a third measuring direction (z) is oriented at right angles to the first and second measuring direction (x, y), and - on the first scale (M2; 20; 120; 220; 320), an illumination beam emitted by a light source (31.1) is split into at least two partial beams, and - the partial beams subsequently strike the second scale (M1; 10; 110; 210; 310), which is arranged to be tilted with respect to the horizontal movement plane about the direction of its longitudinal extent, wherein the partial beams experience back-reflection on the second scale (M1; 10; 110; 210; 310) in the direction of the first scale (M2; 20; 120; 220; 320), and - the back-reflected partial beams strike the first scale (M2; 20; 120; 220; 320) again and are recombined there, so that a resultant signal beam is then propagated in the direction of a detection unit, via which a plurality of phase-shifted scanning signals with respect to the relative movement of the scales (M1, M2; 10, 20; 110, 120; 210, 220; 310, 320) along the third measuring direction (z) and the first or second measuring direction (x, y) can be generated.