Provided are a surface characteristic evaluation apparatus and a surface characteristic evaluation method which evaluate the residual stress of a steel material subjected to a surface modification process while taking the depth direction into account. This surface characteristic evaluation apparatus is provided with an oscillator, a detector, and a measuring instrument. The steel material is set in contact with or in proximity to a coil included in the detector. An alternating current is applied from the oscillator to the coil, and a computation is performed on the basis of a signal representing an electrical characteristic across the coil. This operation is repetitively performed while the frequency of the alternating current is continuously varied, to evaluate the residual stress of the steel material. The coil has a self-resonant frequency higher than the operating frequencies.
