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 plurality of first image data; a processing unit for generating a plurality of focus position data indicating a position of an observation surface of the object in a light-axis direction of the imaging unit at a plurality of different positions in the direction perpendicular to the light-axis direction of the imaging unit, based on the plurality of pieces of first image data captured by the imaging unit with the focus position of the imaging unit relatively different in the light-axis direction of the imaging unit by a moving operation that moves at least one of the imaging unit and the placement unit along the light-axis direction of the imaging unit; a memory for storing a region presentation image based on the plurality of first image data and the plurality of focus position data associated with each other, the plurality of focus position data corresponding to a plurality of different regions within the region presentation image wherein the region presentation image is either extracted from the plurality of first image data or is synthesized from the plurality of first image data; a display unit for displaying the region presentation image stored in the memory; an operation unit for designating a specified region of a part of the region presentation image displayed by the display unit as an observation object region; and a control unit for moving the placement unit in the direction perpendicular to the light-axis direction of the imaging unit to a position corresponding to the observation object region designated by the operation unit, and for performing a focusing operation controlling at least one of the imaging unit and the placement unit based on the focus position data stored in the memory and included in the observation object region designated by the operation unit.