Abstract: A microscope whose enlargement magnification is changeable includes a plurality of interchangeable first objective lenses of different focal lengths for changing a divergent light flux from an object on a stage into a parallel light flux, a first interchanging device for moving the first objective lenses and interchangeably installing them on a predetermined optic axis, a plurality of interchangeable second objective lenses of different focal lengths for condensing the parallel light flux from the first objective lenses and forming an enlarged image of the object at a predetermined position, an eyepiece for observing therethrough the enlarged image of the object formed by the second objective lenses, a prism for directing the light flux from the second objective lenses to the eyepiece, and a second interchanging device provided between the first interchanging device and the prism for moving the second objective lenses and interchangeably installing them on the predetermined optic axis.