A thin film gas-sensitive device includes an insulating substrate having a pair of electrodes, a gas-sensitive layer having a gas sensitive substance deposited on the insulating substrate and electrodes, and a catalytic layer deposited on the gas-sensitive layer and insulating substrate as a non-continuous layer. The insulating substrate is partly uncovered because the electrodes, the gas-sensitive layer containing the gas-sensitive substance and the catalytic layer do not thoroughly cover the substrate.