An exposure apparatus for exposing a substrate via a projection optical system, the apparatus comprising: a frame member arranged to support the projection optical system; a substrate stage disposed below the projection optical system supported by the frame member, and arranged to hold the substrate; an encoder system configured to measure positional information of the substrate stage, by irradiating a grating member (39X 1, 39X 2, 39Y 1, 39Y 2) having a grating surface with a measurement beam from a direction intersecting a predetermined plane via each of a plurality of heads (64, 65, 66), the grating surface having a reflection type grating formed thereon and being disposed substantially parallel to the predetermined plane, and the predetermined plane being orthogonal to an optical axis of the projection optical system; a drive system configured to drive the substrate stage; and a control system configured to control driving of the substrate stage by the drive system, based on the positional information measured with multiple heads, the multiple heads being a part of the plurality of heads of the encoder system, wherein in the encoder system, one of the grating member and the plurality of heads is provided to the substrate stage, and the other of the grating member and the plurality of heads is supported by the frame member, and one of the multiple heads used in driving control of the substrate stage is switched to another head, of the plurality of heads, according to movement of the substrate stage, and the control system is configured to determine the positional information to be measured with the another head to be used after the switching based on the positional information measured with the multiple heads used before the switching, and characterised in that the control system is capable of using each of a first method and a second method in the switching, in the first method, an offset for the another head to be used after the switching being reset so that the positional information measured before and after the switching coincide, and in the second method, a part of an offset that has been already set for the another head to be used after the switching being continuously used also after the switching. a frame member arranged to support the projection optical system; a substrate stage disposed below the projection optical system supported by the frame member, and arranged to hold the substrate; an encoder system configured to measure positional information of the substrate stage, by irradiating a grating member (39X 1, 39X 2, 39Y 1, 39Y 2) having a grating surface with a measurement beam from a direction intersecting a predetermined plane via each of a plurality of heads (64, 65, 66), the grating surface having a reflection type grating formed thereon and being disposed substantially parallel to the predetermined plane, and the predetermined plane being orthogonal to an optical axis of the projection optical system; a drive system configured to drive the substrate stage; and a control system configured to control driving of the substrate stage by the drive system, based on the positional information measured with multiple heads, the multiple heads being a part of the plurality of heads of the encoder system, wherein in the encoder system, one of the grating member and the plurality of heads is provided to the substrate stage, and the other of the grating member and the plurality of heads is supported by the frame member, and one of the multiple heads used in driving control of the substrate stage is switched to another head, of the plurality of heads, according to movement of the substrate stage, and the control system is configured to determine the positional information to be measured with the another head to be used after the switching based on the positional information measured with the multiple heads used before the switching, and characterised in that the control system is capable of using each of a first method and a second method in the switching, in the first method, an offset for the another head to be used after the switching being reset so that the positional information measured before and after the switching coincide, and in the second method, a part of an offset that has been already set for the another head to be used after the switching being continuously used also after the switching.