A focus detecting apparatus according to one aspect of the disclosure includes at least one processor, and a memory coupled to the at least one processor, the memory having instructions that, when executed by the processor, perform operations as a first determining unit configured to determine an image stabilizing area based on object information, and a second determining unit configured to determine a focus detecting area based on the object information, and to determine a calculation area for focus detection based on the focus detecting area. The second determining unit determines the calculation area based on a relationship between the image stabilizing area and the focus detecting area. An image pickup apparatus having the above focus detecting apparatus, a focus detecting method corresponding to the above focus detecting apparatus, and a storage medium storing a program that causes a computer to execute the above control method also constitute another aspect of the disclosure.