Photoacoustic measurements for the polycrystalline samples of orthorhombic GdBa2Cu3O7−xand DyBa2Cu3O7−xhave been carried out in the temperature region around the superconducting transition. The relative values of the specific heat for the superconducting samples are obtained from the photoacoustic signal by using the thermal conductivity data measured by the longitudinal heat flow method and show a good agreement with the specific heat data measured using a calorimetric method by others. The usefulness of the photoacoustic technique for the specific heat measurement is confirmed by the photoacoustic measurement of KDP(KH2PO4) sample near the phase transition.