An exposure apparatus for forming a pattern on an object by an irradiation of an energy beam, the apparatus comprising: a patterning device for irradiating the energy beam on the object; and a movable body drive system for driving a movable body in a movement plane including a first axis and a second axis orthogonal to each other, wherein the movable body drive system is configured to drive the movable body on which the object is mounted for relative movement of the energy beam and the object, the movable body drive system comprising: an encoder system having a plurality of heads (64, 66) and a grating, each head being for irradiating a detection light on the grating and for receiving the detection light from the grating, the plurality of heads including a first head and a second head, the first head being usable for measuring positional information of the movable body in a direction parallel to the first axis, and the second head being usable for measuring positional information of the movable body in a direction parallel to the second axis; and a controller configured to measure positional information of the movable body in the movement plane using at least three heads of the encoder system, and also to switch at least one head used for measurement of the positional information of the movable body in the movement plane to another head so as to maintain a position of the movable body in the movement plane before and after the switching, the at least three heads including at least one each of the first head and the second head, and the another head being different from the at least three heads, wherein the controller is configured to predict a measurement value of the another head based on the positional information measured by the at least three heads so that a result of position measurement of the movable body is continuously linked before and after the switching and to set the predicted measurement value as an initial value of the measurement value of the another head. a patterning device for irradiating the energy beam on the object; and a movable body drive system for driving a movable body in a movement plane including a first axis and a second axis orthogonal to each other, wherein the movable body drive system is configured to drive the movable body on which the object is mounted for relative movement of the energy beam and the object, the movable body drive system comprising: an encoder system having a plurality of heads (64, 66) and a grating, each head being for irradiating a detection light on the grating and for receiving the detection light from the grating, the plurality of heads including a first head and a second head, the first head being usable for measuring positional information of the movable body in a direction parallel to the first axis, and the second head being usable for measuring positional information of the movable body in a direction parallel to the second axis; and a controller configured to measure positional information of the movable body in the movement plane using at least three heads of the encoder system, and also to switch at least one head used for measurement of the positional information of the movable body in the movement plane to another head so as to maintain a position of the movable body in the movement plane before and after the switching, the at least three heads including at least one each of the first head and the second head, and the another head being different from the at least three heads, an encoder system having a plurality of heads (64, 66) and a grating, each head being for irradiating a detection light on the grating and for receiving the detection light from the grating, the plurality of heads including a first head and a second head, the first head being usable for measuring positional information of the movable body in a direction parallel to the first axis, and the second head being usable for measuring positional information of the movable body in a direction parallel to the second axis; and a controller configured to measure positional information of the movable body in the movement plane using at least three heads of the encoder system, and also to switch at least one head used for measurement of the positional information of the movable body in the movement plane to another head so as to maintain a position of the movable body in the movement plane before and after the switching, the at least three heads including at least one each of the first head and the second head, and the another head being different from the at least three heads, wherein the controller is configured to predict a measurement value of the another head based on the positional information measured by the at least three heads so that a result of position measurement of the movable body is continuously linked before and after the switching and to set the predicted measurement value as an initial value of the measurement value of the another head.