An optical apparatus attachable to an image pickup apparatus and switchable a power state between a first state and a second state that consumes a power less than the first state includes a driver that drives a driven member, a first detector configured to detect a driving amount of the driver or whether the driven member is located at a predetermined position, a memory that stores a signal value of the first detector when the power state of the optical apparatus is switched from the first state to the second state, and a determiner that determines that the driver is in an abnormal state when the signal value stored in the memory and the signal value of the first detector when the power state of the optical apparatus is switched from the second state to the first state are different from each other.