1. A magnification observation device which images an object to display an image of the object, comprising: a placement unit on which the object is mounted; an imaging unit for imaging the object mounted on the placement unit to capture a first image data; a display unit for displaying an image of the object as a region presentation image based on the first image data captured by the imaging unit; a processing unit for generating focus position data indicating the position of observation surface of the object in the light-axis direction of the imaging unit, based on the first image data captured by the imaging unit; an operation unit being operated by a user for designating a region of the object to be observed as an observation object region in the region presentation image displayed by the display unit; and a control unit for performing a focusing operation controlling at least one of the imaging unit and the placement unit so that a focus of the imaging unit is on the observation surface in the observation object region designated by the operation of the operation unit, based on the focus position data generated by the processing unit.