A system comprises: a measurement unit adapted to measure a position/orientation of at least one target object based on an image obtained by capturing the at least one target object; a selection unit adapted to select at least one grippable target object based on the position/orientation; a determination unit adapted to determine, as an object to be gripped, a grippable target object in a state with a highest priority from the at least one grippable target object based on priorities set in advance for states including gripping positions/directions; a gripping unit adapted to grip the object to be gripped in the state with the highest priority; and a changing unit adapted to change the state of the gripped object, to a state in which the gripped object is assembled to the other object.