An apparatus for evaluating an epitaxial layer, including pre-treating the epitaxial layer before evaluation of the epitaxial layer by making the epitaxial layer contact with a metal electrode by a capacitance-voltage measurement, the method comprising; applying carbon-bearing compound to a surface of the epitaxial layer; subsequently irradiating ultraviolet light to the surface of the epitaxial layer; and thereby forming an oxide film on the surface of the epitaxial layer.An apparatus for evaluating an epitaxial layer of an epitaxial wafer, the apparatus including a pretreatment unit for pre-treating an epitaxial wafer having a semiconductor wafer and an epitaxial layer formed on the semiconductor wafer, a metal-electrode which can be made contact with or vapor-deposited on the surface of the epitaxial layer of the epitaxial wafer which has been pre-treated in the pretreatment unit, a measuring electrode which can be made contact with or vapor-deposited on the semiconductor wafer, and a measuring unit which is connected to each of the electrodes and is used to measure physical properties of the epitaxial layer. The pretreatment unit includes an applying device for applying a carbon-bearing compound to a surface of the epitaxial layer, and an irradiation device for irradiating ultraviolet light to the surface of the epitaxial layer in an oxygen-bearing atmosphere.