This paper describes a numerical analysis for the shear horizontal surface acoustic wave (SH-SAW) immunoassay biosensor. A numerical calculation method which was proposed by Campbell and Jones has been generally used to calculate SAW propagation characteristics. In this paper, a numerical calculation method for SH-SA W propagation characteristics is proposed, which is an improved Campbell and Jones method involving an influence of liquid viscosity. In order to confirm the proposed numerical analysis, 250 MHz SH-SA W delay-lines on quartz substrates were tested using glycerol-water mixed liquids of different concentrations of 0, 10, 20 and 30 wt%. In the experiments, the velocity changes and attenuation changes of the SH-SA Ws were increased increment in glycerol concentrations as theoretically expected. Very good agreements between theoretical and experimental results were obtained.