POCT（Point of Care Testing）which is a diagnostic testing at or near the patients has been required for the near future medical and healthcare systems. In this paper, an immunoassay-based biosensor using shear-horizontal surface acoustic wave（SAW）devices for POCT applications is described. A temperature-stable 250 MHz delay-line type SAW biosensor was fabricated on quartz substrates. SAW velocity changes due to antigen-antibody reactions were observed as we expected and quantitative results were obtained. In addition, a working prototype of SAW biosensors which connects to a smart-phone was demonstrated for future home healthcare applications.