We demonstrated a capability of biomechanical characterization by photoacoustic measurement for the purpose of non-invasive functional evaluation of articular cartilage. In this study, the scheme of photoacoustic measurement was improved. For in vivo application, the measurement scheme was changed from a transmittance mode to a reflectance mode in which an optical fiber was coaxially arranged with a piezoelectric transducer. In order to verify the applicability of this measurement for diagnosis of cartilage degeneration, photoacoustic measurements in a reflectance mode were performed using various degenerated cartilages. As a model of degenerated cartilage, cartilage-bone plugs were punched out from a porcine knee joint and treated with trypsin (1 mg/ml). Stress waves were induced by 250-355 nm, 7-ns light pulses delivered through an optical silica fiber from an OPO and were detected by a piezoelectric transducer. The change in relaxation time, which was correlated with the viscosity-elasticity ratio, had a positive correlation with time of trypsin treatment. Our results revealed the applicability of photoacoustic measurement to in vivo preoperative diagnosis of cartilage degeneration.