Nowadays, there has been a growing interest in wireless sensor networks. One of the major issues in wireless sensor network is developing an energy-efficient routing protocol. LEACH is very energy-efficient routing protocol based on the clustering of the sensor nodes. However, energy consumption of nodes tends to become uneven in LEACH. HEED improves the LEACH clustering algorithm by using information of residual electric power of nodes. Although HEED provides better performance than LEACH, it does not consider the number of adjacent nodes. Therefore, the cluster head does not efficiently cover the nodes in HEED. HIT is based on the small transmission range and multi-hop communication. Though HIT has improved the performance dramatically, unbalance of the electric power consumption is remained. In this paper, we propose energy-efficient clustering algorithm considering adjacent nodes and residual electric power. In addition, we inspect effectiveness of our method by comparing our method with the traditional method by the simulation.