The effect of cyclotron resonance absorption upon laser‐induced gas breakdown is calculated. It is shown that the threshold power for breakdown is dramatically reduced at resonance. The calculations are carried out in the limits of both short and long laser pulses. In the short‐pulse limit, the threshold power is determined by the length of laser pulse; in the long‐pulse limit, it is determined by electron diffusion from the breakdown region and by energy loss resulting from elastic collisions.