We have measured the electrical resistivity and the magnetoresistance (MR) of polycrystalline CePd2Ga3 under high pressure and low temperature. CePd2Ga3 is ferromagnetically ordered compound with TC=7.0K at ambient pressure. The magnetic ordering temperature decreased up to 3.4GPa, though it increased slightly at 3.8GPa. The negative MR at 0.1K became larger at higher pressure, however, turned into positive above 2.1GPa. The positive MR was quite large, suggesting an enhancement of magnetic instability. Above 2.3GPa, the MR became negative again and showed a different character at 3.8GPa. These properties claim that the magnetism of CePd2Ga3 changes into antiferromagnetsm.