A method of forming a tire innerliner having a cylindrical inner rubber layer and a cylindrical film formed of a thermoplastic resin or a thermoplastic elastomer composition having a thermoplastic resin and an elastomer blended therewith. The cylindrical film is disposed radially outwardly of the cylindrical inner rubber layer. The method includes the following steps: wrapping an unvulcanized rubber layer cylindrically around a building drum to form the cylindrical inner rubber layer; and subsequently wrapping a sheet-shaped film formed of a thermoplastic resin or a thermoplastic elastomer composition having a thermoplastic resin and an elastomer blended therewith cylindrically around the cylindrical inner rubber layer, which is already wrapped around the building drum, to form the cylindrical film. The unvulcanized rubber layer constituting the cylindrical inner rubber layer is a strip-shaped rubber layer, and the cylindrical inner rubber layer is formed by spirally winding the strip-shaped rubber layer.