We fabricated a prototype for detecting hydrogen gas leaks in hydrogen filling stations. The prototype is composed of a wireless network with ten sensor nodes that can monitor the spatial distribution of hydrogen gas leakage. To enable each sensor node to be driven by a battery, field-effect-transistor sensors and a microprocessor with low power consumption have been adopted. Additionally, a function to consume minimal levels of power has been developed and installed in the microprocessor in each node. The use of batteries and wireless communications enables the nodes to be placed at optimal sensing locations without regard to the wiring needed with existing gas sensors.