Provided is a film forming method, etc., whereby a powdered material can be rapidly jetted while excessive heating of the powdered material is suppressed in a cold spray method. A film forming method for forming a coating by spray-depositing a powdered material in a solid-phase state onto the surface of a substrate, the film forming method including: a mixing length adjustment step for adjusting the distance between the position of minimum diameter of a penetration passage which decreases in diameter progressively from a proximal-end part to a distal-end part and then increases in diameter, and a mixing position where the powdered material introduced to a nozzle is mixed with a gas, in accordance with the type of the powdered material; a jetting step for mixing the powdered material and a gas at the mixing position and introducing the mixture to the nozzle, accelerating the powdered material and the gas toward the smallest-diameter position, and jetting the powdered material and the gas from the distal-end pa
