1. An image pickup apparatus provided with a solid state image pickup device and a data compression means for compressing a video signal acquired by said solid state image pickup device, characterized in that said image pickup apparatus comprises: a characteristic value calculation means for extracting a characteristic value used for predicting an amount of codes to be generated at a time of compressing a video signal acquired by said solid state image pickup device from the video signal; and a compression coefficient control means for controlling a compression coefficient which is used by said data compression means based on the characteristic value acquired by said characteristic value calculation means, said compression coefficient control means using the characteristic value acquired by said characteristic value calculation means at a time of allowing users to check an image to be picked-up before picking up the image, and determining the compression coefficient at a time of picking up an image.