The present invention provides a deformation apparatus that deforms a surface of a member, the apparatus comprising: a plurality of actuators each of which is configured to apply a force to the member to deform the surface; a measurement device configured to measure an induced electromotive force generated in a first actuator of the plurality of actuators; and a controller configured to control the plurality of actuators, wherein the controller causes the measurement device to measure a temporal variation of an induced electromotive force in the first actuator while vibrating the member by using a second actuator, of the plurality of actuators, which is different from the first actuator, converts the measured temporal variation of the induced electromotive force into a frequency spectrum, and detects an abnormality in the first actuator based on the frequency spectrum.