Disclosed is a wireless sensor network with a linear structure capable of bidirectional communication. The wireless sensor network includes a plurality of nodes linearly connected from a sink node to a terminal node by connecting each node to a single upper-level node and a single lower-level node, each node has an active period for transmitting/receiving data to/from its upper-level node and lower-level node, the active period includes a downstream duration for transmitting data/commands from the sink node to the terminal node and an upstream duration for transmitting data/commands from the terminal node to the sink node, and each of the upstream and downstream durations sequentially includes RX, TX, and ACK intervals, so that bidirectional communication between the sink node and the terminal node can be performed within a single active period.