An image pickup apparatus whose function can be easily changed is provided. The image pickup apparatus, to which a mounting component part having a wireless IC tag can be attached, comprising at least one processor and/or circuit configured to function as following units, a reading unit configured to read information recorded in the wireless IC tag, an attitude determination unit configured to determine an attitude of the mounting component part, which is attached, with respect to the image pickup apparatus, and a function changing unit configured to change a function of the image pickup apparatus. In a case that the reading unit can read the information recorded in the wireless IC tag, the function changing unit changes the function of the image pickup apparatus according to the attitude of the mounting component part, which is determined.