We studied the superconducting properties of Pd hydride and deuteride prepared by a low temperature absorption method using in situ magnetization measurements down to T = 0.5 K. The absorption was performed under hydrogen (H₂) or deuterium (D₂) gas atmosphere at T = 200 K, where the gas pressure and magnetization were monitored simultaneously. From the pressure change caused by the absorption of H (D) in Pd sample, the H (D) content was determined to be 0.82 (0.79). The superconducting state was observed below T ∼ 1.3 K for the both systems. This state was investigated through precise magnetization measurements. The results suggest that H or D atoms are absorbed uniformly over the whole sample.