A protein chip based on surface plasmon resonance(SPR) imaging was developed for measuring classical swine fever virus(CSFV) antibody using a recombinant gp55 protein as an antigen. The diagnostic potential of SPR imaging for detecting antibodies to the CSFV gp55 protein was compared with that of a enzyme-linked immunosorbent assay(ELISA) using 70 pig sera. There was a strong positive correlation between the SPR imaging and ELISA(n=70, r=0.916, p<0.01). Therefore, the SPR imaging, which is a label-free and high-through put method, is expected to be a valuable tool in the serodiagnosis of CSFV.