The present invention provides a scanning exposure apparatus and a device manufacturing method. The scanning exposure apparatus exposes a mask pattern to the photosensitive layer of a substrate, and comprises: light source parts which are arranged, when a slit-shaped illumination area illuminated by illumination light is divided into multiple partial illumination regions long in the first direction and short in the second direction, corresponding to the number of the plurality of partial illumination regions, and emit light beams having the same illuminance distribution respectively; a plurality of optical members arranged along the first direction and converting light beams emitted from the light source parts into illumination light long in the first direction and short in the second direction in accordance with the shape of each of the plurality of partial illumination regions; and a plurality of deflection members arranged corresponding to the plurality of partial illumination regions respectively along the first direction, and the illumination light emitted from each of the plurality of optical members is deflected with respect to the second direction so as to be directed to the plurality of partial illumination regions respectively when viewed in the first direction.