An image pickup apparatus which can detect, when pixels have a structure in which part of electrical construction is shared therebetween, a defective pixel by taking into account a high possibility of the other pixels sharing the part of electrical construction becoming defective pixels, thereby making it possible to obtain an excellent image. A ROM stores in advance position information on each defective pixel. A defective pixel-detecting section detects a new defective pixel on which position information is not stored by the storage unit, from the pixels forming each pixel group, by performing one of different types of defective pixel detection processing. A system controller causes the defective pixel-detecting section to execute one of the different types of detection processing, according to the number of defective pixels which are included in each pixel group and on which the position information is stored in the storage unit.