PURPOSE: To mold integrally a thin urethane foam without generating defective bonded sections and the like by injecting urethane raw liquid into a rear face of a skin material set on a bottom force, spraying air to spread the raw liquid all over the rear face of the skin material thin and evenly, and then closing top and bottom forces to carry out a foam molding.

CONSTITUTION: A skin material 14 is set in a cavity 28 of a bottom force 30. Then the given quantity of urethane raw liquid 32 is injected onto a rear face of the skin material 14 by an urethane raw liquid injection nozzle 34 fitted in a robot hand. Successively air is sprayed from an air nozzle 36 to the urethane raw liquid 32 to flow the raw liquid 32 forcibly to spread the raw liquid all over the rear face of the skin material 14 quickly, uniformly and thinly. Then the bottom force 30 is closed with a top force on which an insert material is set. Thus a given clearance is formed between the insert material and the skin material, and foam molding is carried out integrally.