Utilities of wireless sensor networks are standing out in bold relief in various fields such as home environmental, industrial, and military applications. Compared with the vivid applications of the sensor networks, however, the security and privacy issues of the sensor networks are still in their infancy because unique features of the sensor networks make it difficult to adopt conventional security policies. Especially, false reports are critical threats because they can drain out the finite amount of energy resources in a battery-powered sensor networks; thus, a novel trust management scheme is necessary to make resilient wireless sensor networks. Cryptographic authentication mechanisms and key management schemes cannot suggest solutions for the real root of the problem. In this paper, we propose a trust management scheme which can identify trustworthiness of sensor nodes and suggest a defensible approach against insider attacks beyond conventional cryptographic approaches.