An image pickup apparatus includes: an image data production unit configured to produce data of a plurality of kinds of images from a picked up image and successively output the data; an image synthesis unit configured to cyclically connect the data of the plurality of kinds of images for each pixel string within a range set in advance for each of the kinds of the images and output the connected data as a stream to produce a virtual synthetic image; and an image sending unit configured to accept, from a host terminal, a data transmission request that designates a rectangular region in the virtual synthetic image, extract and connect data from the stream and transmit the connected data as a new stream to the host terminal.