Examples of a plasma film forming method include repeating feeding material gas onto a substrate placed on a susceptor via a shower head provided to oppose the susceptor, performing plasma film formation on the substrate by applying high frequency power to the shower head while providing reactant gas onto the substrate, and performing post-purge of discharging the gas used in the plasma film formation while heating the shower head, for a time longer than 0.1 seconds, a plurality of times in this order.