There is provided an image pickup system for endoscope including: a light source; an image forming optical system; a focus lens driving section; an image pickup section outputting an image signal; an image signal amplifying section; an image brightness detecting section; a brightness adjusting section adjusting a brightness control condition such as a light quantity of the light source, an image pickup condition of the image pickup section and an amplification factor of the amplifying section so that brightness of an image becomes a predetermined brightness; an auxiliary AF section estimating a temporary focus position based on the brightness control condition; a control section setting a small scanning range including the temporary focus position; and a contrast AF section causing contrast AF to be performed in the scanning range.