An object characteristics measurement apparatus (10, 10a, 46, 78), comprising a surface acoustic wave device (12, 12a, 44, 76), a measurement unit (20, 54) and a processor (22, 56), the surface acoustic wave device (12, 12a, 44, 76) comprising: an interdigitated electrode (26, 60a, 60b) 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 (30, 64, 500-504) that has a third surface and a fourth surface between the interdigitated electrode (26, 60a, 60b) and a second surface orthogonal to the first surface of the piezoelectric substrate in a propagation direction of the elastic wave, the third surface being formed at a position different from that of the first surface in a normal direction of the first surface, the fourth surface connecting an end of the first surface, which is formed perpendicular to the normal direction of the first surface, to the third surface; a reaction field (32, 66a, 66b) that is formed between the interdigitated electrode (26, 60a, 60b) and the reflector (30, 64, 500-504), in which the measured object is to be loaded; and a propagator (34, 68) that is formed between the reflector (30, 64, 500-504) and the second surface, the measurement unit (20, 54) being connected to the interdigitated electrode (26, 60a, 60b) and comprising an elastic wave detector (18, 52) supplying a signal to the processor (22, 56), the processor (22, 56) being configured to separate and extract a surface acoustic wave signal associated with a surface acoustic wave, from bulk wave signals associated with bulk waves, and to determine characteristics of the measured object based on the extracted surface acoustic wave signal, the surface acoustic wave propagating along the reaction field (32, 66a, 66b) from the interdigitated electrode (26, 60a, 60b), the surface acoustic wave being reflected by the fourth surface of the reflector (30, 64, 500-504), the surface acoustic wave propagating along a surface of the piezoelectric substrate which is included in the elastic wave that is received by the interdigitated electrode (26, 60a, 60b), the bulk wave being reflected by the second surface of the piezoelectric substrate, the bulk wave propagating through an inside of the piezoelectric substrate which is included in the elastic wave that is received by the interdigitated electrode (26, 60a, 60b). an interdigitated electrode (26, 60a, 60b) 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 (30, 64, 500-504) that has a third surface and a fourth surface between the interdigitated electrode (26, 60a, 60b) and a second surface orthogonal to the first surface of the piezoelectric substrate in a propagation direction of the elastic wave, the third surface being formed at a position different from that of the first surface in a normal direction of the first surface, the fourth surface connecting an end of the first surface, which is formed perpendicular to the normal direction of the first surface, to the third surface; a reaction field (32, 66a, 66b) that is formed between the interdigitated electrode (26, 60a, 60b) and the reflector (30, 64, 500-504), in which the measured object is to be loaded; and a propagator (34, 68) that is formed between the reflector (30, 64, 500-504) and the second surface, the measurement unit (20, 54) being connected to the interdigitated electrode (26, 60a, 60b) and comprising an elastic wave detector (18, 52) supplying a signal to the processor (22, 56), the processor (22, 56) being configured to separate and extract a surface acoustic wave signal associated with a surface acoustic wave, from bulk wave signals associated with bulk waves, and to determine characteristics of the measured object based on the extracted surface acoustic wave signal, the surface acoustic wave propagating along the reaction field (32, 66a, 66b) from the interdigitated electrode (26, 60a, 60b), the surface acoustic wave being reflected by the fourth surface of the reflector (30, 64, 500-504), the surface acoustic wave propagating along a surface of the piezoelectric substrate which is included in the elastic wave that is received by the interdigitated electrode (26, 60a, 60b), the bulk wave being reflected by the second surface of the piezoelectric substrate, the bulk wave propagating through an inside of the piezoelectric substrate which is included in the elastic wave that is received by the interdigitated electrode (26, 60a, 60b).