Power-saving method for wireless sensor network

A power-saving method of wireless communication device, which operates a sleep mode for minimizing power consumption except for an active mode for communication, initializes a sleep probability upon the device being turned on, operates the active mode for communication with starting an active mode timer, transits to the sleep mode when there is no packet to transmit or receive before the active mode timer expires; and determines an exit from the sleep mode on the basis of the sleep probability.