An exposure apparatus for exposing an object with an exposure beam via a projection optical system, the apparatus comprising: a movable body (WST1, WST2) arranged to hold the object and to move along a predetermined plane; a position measurement system (70, 71) arranged to obtain positional information of the movable body based on an output of each of heads, each of which is arranged to irradiate a measurement beam on a scale plate placed roughly parallel to the predetermined plane external to the movable body in the vicinity of an exposure position of the object and to receive a return beam from the scale plate, the heads being of a plurality of heads (60 1, 60 2, 60 3, 60 4) provided on the movable body; and a control system arranged to drive the movable body based on the positional information obtained by the position measurement system, and to switch one head of the plurality of heads which the position measurement system uses to obtain the positional information to another head of the plurality of heads according to the position of the movable body, wherein the scale plate comprises a plurality of sections (21 1, 21 2, 21 3, 21 4) each of which having a grating formed thereon, and an exposure time movement area is an area in which the movable body moves during an exposure operation, the exposure operation including exposure of the object that is performed via the projection optical system; and while the movable body is positioned within the exposure time movement area, each head of the plurality of heads either faces a corresponding section of the scale plate, or does not face a section of the scale plate; the control system is configured to obtain an offset for correcting a measurement error between positional information obtained based on an output of each of a predetermined number of heads that belong to a first head group of the plurality of heads and positional information obtained based on an output of each of a predetermined number of heads that belong to a second head group of the plurality of heads, the offset being obtained while the movable body is positioned within a first movement area in which each of the heads belonging to the first head group and the heads belonging to the second head group faces the scale plate. a movable body (WST1, WST2) arranged to hold the object and to move along a predetermined plane; a position measurement system (70, 71) arranged to obtain positional information of the movable body based on an output of each of heads, each of which is arranged to irradiate a measurement beam on a scale plate placed roughly parallel to the predetermined plane external to the movable body in the vicinity of an exposure position of the object and to receive a return beam from the scale plate, the heads being of a plurality of heads (60 1, 60 2, 60 3, 60 4) provided on the movable body; and a control system arranged to drive the movable body based on the positional information obtained by the position measurement system, and to switch one head of the plurality of heads which the position measurement system uses to obtain the positional information to another head of the plurality of heads according to the position of the movable body, wherein the scale plate comprises a plurality of sections (21 1, 21 2, 21 3, 21 4) each of which having a grating formed thereon, and an exposure time movement area is an area in which the movable body moves during an exposure operation, the exposure operation including exposure of the object that is performed via the projection optical system; and while the movable body is positioned within the exposure time movement area, each head of the plurality of heads either faces a corresponding section of the scale plate, or does not face a section of the scale plate; the control system is configured to obtain an offset for correcting a measurement error between positional information obtained based on an output of each of a predetermined number of heads that belong to a first head group of the plurality of heads and positional information obtained based on an output of each of a predetermined number of heads that belong to a second head group of the plurality of heads, the offset being obtained while the movable body is positioned within a first movement area in which each of the heads belonging to the first head group and the heads belonging to the second head group faces the scale plate.