PURPOSE: To provide a magnifying lens capable of increasing an magnification of a microscope having a high performance with simple and compact optical constitution by arranging plural lens groups into the convergent luminous flux formed by an objective optical system for the microscope and converting a space image to a prescribed magnification.

CONSTITUTION: The microscope is provided with the magnifying lens 7 which converts the luminous flux from an object 5 to be observed to the convergent luminous flux and increases the magnification of the objective optical system 6 for the microscope forming the space image I0 of an object 5 to be observed to the prescribed magnification. This magnifying lens 7 has the plural lens groups of negative refracting powers which are independently corrected in aberrations. The space image I0 is converted to the prescribed magnification by arranging the plural lens groups G1, G2 in the convergent luminous flux formed by the objective optical system 6 for the microscope. As a result, there is no more need for providing the objective optical system with many relay systems for obtaining the large magnification in series and the large magnification is obtd. while the size of the optical system constituting the microscope is reduced and the performance thereof is enhanced.