An image capturing system includes a smartphone serving as an imaging unit, and a mounting stand to be disposed on a medium setting surface on which a medium serving as a reading target is set. The mounting stand has a placement surface on which the smartphone is placed at a position allowing the smartphone to image the medium set on the medium setting surface. When generating a starting trigger based on image information of an imaging area in the state where the smartphone is placed on the mounting stand, the smartphone executes a function (scanning operation) associated with the starting trigger.