An image pickup apparatus operating in a moving picture photographing mode, wherein, before a start of moving picture photographing is indicated by a shutter button on a key input section, a clock frequency of a control section is made to be a normal frequency so that electricity consumption is reduced in a monitoring state to lengthen the life of a battery, and wherein, when the start of moving picture photographing is indicated, the clock frequency is increased to a large extent by a clock switching control section, so that an MPEG converter can access at a high speed an SDRAM storing YUV data such as reference data, search data, or the like at the time of encoding processing of moving picture data, and the moving picture compression can be achieved in real-time.