An object characteristics measurement apparatus of the invention includes a surface acoustic wave device. The surface acoustic wave device includes: an interdigitated electrode that is formed on a first surface on a piezoelectric substrate, excites an elastic wave, and receives reflection based on the elastic wave; a reflector that has a third surface and a fourth surface between the interdigitated electrode and a second surface orthogonal to the first surface in a propagation direction of the elastic wave; a reaction field that is formed between the interdigitated electrode and the reflector, in which the measured object is to be loaded; and a propagator that is formed between the reflector and the second surface.