Most of wireless sensor network nodes are powered not by main power but by batteries. A node which runs out of batteries cannot serve as a component of a network. This is why minimizing energy consumption of a node is important. Energy is consumed with various environment such like sensing, data processing data communication and so on, and especially data communication is a big consumer. Currently, many works for reducing data communication energy have been devised and most of them are about communication sleep mode and MAC protocol. The basic idea of our work is that a node emits signal with uniform power regardless of a distance and this wastes energy when a node communicates with a nearby node. In this paper, we propose a novel method which can vary a transmission power according to a distance with a destination node to minimize energy consumption of a node. And it can be also served to minimize energy consumption over a whole network and provide an energy-minimal routing path.