Relapsing polychondritis (RP) is a disorder of unknown etiology characterized by the destruction of cartilage. A case of RP in a 59‐year‐old male was autopsied, and systemic inflammation of various cartilages was confirmed. We demonstrated the circulating antibodies to Type II (cartilage) collagen. No antibodies to other collagen types were demonstrated. The presence of granular deposits of immunoglobulins, fibrinogen, and the C3 component of complement at the chondrofibrous junction was also demonstrated. From these findings, this case suggested that the pathogenesis of RP is related to an immune mechanism.