1. An image capturing apparatus, comprising: an image capturing unit including: an image capturing section that captures an image; an image compressing section that compresses the image captured by said image capturing section and produces a compressed image; a first memory having a first memory capacity that stores the image captured by said image capturing section and the compressed image, and wherein said first memory requires a first power consumption; a first display section that displays the compressed image and having a first number of pixels which is less than that of said image captured by said image capturing section, and a large memory unit which is removable from said image capturing unit, comprising a second memory having a second memory capacity which is larger than said first memory capacity of said first memory, said second memory storing the image transferred from said first memory when a predetermined condition is met, said second memory requires a second power consumption which is larger than said first power consumption of said first memory, wherein said first memory requires less power consumption in reading an image of the same capacity out thereof than that in reading out of said second memory, wherein said second memory is a hard disk drive and said first memory is a semiconductor memory, a battery that feeds operating power to said image capturing section, said second memory, said first memory, said image compressing section, and said first display section, wherein said image capturing unit further includes a storage processing section which transfers a plurality of images captured by said image capturing section altogether to said second memory when an empty capacity of said first memory falls below a reference value set in advance, wherein said storage processing section transfers the images captured by said image capturing section from said first memory to said second memory and stores only the compressed images in said first memory when power is supplied from the outside.