A gas switch triggered by μJ laser pulses was developed. The switch employed a 10 mm-gap GaAs photoconductive semiconductor switch (PCSS) mounted in parallel with one of its two gaps. The dark current-voltage characteristic of the PCSS was obtained, and the gas switch characteristics at different bias voltages were experimentally investigated. The results indicate that the switch can be triggered reliably by using a 17 µJ laser pulse, and the jitter is less than 3 ns at the bias voltage of 80 kV and 60% of the self-breakdown voltage.