Space charge behaviours in three types of polyethylene with different resistivities under dc electric field from 1 to 4 MV/cm were observed using improved PEA system. In ordinary low-density polyethylene, a huge amount of positive packet charge was observed. In cross-linked polyethylene, which has a lowest resistivity among them, an oscillatory movement of space charge in the bulk was observed. In improved low-density polyethylene with carbonyl group, which has a highest resistivity among them, any remarkable charge behaviour was not observed.