This paper proposes an electric power based incentive mechanism that source nodes compensate the electric power required for packet transmissions in mobile ad hoc network (MANET). Although MANET forces the relay cooperation on nodes for the multi-hop communication, the relay transmission consumes their resources for other nodes, which may cause nodes to be uncooperative. We assume electric power exchange between nodes, which has been getting practical in recent years. The proposed routing method uses incentive power based on the energy consumption for relaying packets as a metric. Computer simulation confirmed that the method implemented to AODV can reduce the power consumption on the relay nodes.