The investigation regarding the performance of newly developed plasma jet igniter is explored by using vessel. In plasma jet ignition, combustion enhancement effects occur toward the plasma jet issuing direction. Therefore, when the igniter is attached at the center of cylindrically shaped combustion chamber, plasma jet should issue toward the round combustion chamber wall. The plasma jet igniter that had a concentric circular orifice has been developed. The maximum combustion pressure increases and the burning period decreases with increasing the cavity volume. This feature is similar to that of the ordinary plasma jet igniter. However, the combustion enhancement effect is almost independent of the orifice area.