Exposure apparatus and article manufacturing method

An exposure apparatus according to the present invention includes a projection optical system projecting, onto a substrate, exposure light for forming a pattern on the substrate, a light shielding member having an opening for allowing the exposure light to pass therethrough, a focus detecting unit detecting a defocus amount representing a positional deviation between a condensed position of the exposure light and the substrate, a light receiving element receiving a light flux passing through the opening in the light shielding member after being reflected by the substrate, and a control unit moving the light shielding member in a direction of an optical axis of the projection optical system on the basis of a result of detection in the focus detecting unit. The focus detecting unit detects the defocus amount on the basis of the amount of light received by the light receiving element.