The invention discloses a method, a system and a program for supporting design of a magnetron sputtering apparatus. A static magnetic field structure data is read, a cross section which is parallel with the sputtering target surface and in which plasma is generated is specified at a random position, and an erosion center line segment having an endless shape which goes through the center of a region in which the magnetic field vertical to the plane of the specified cross section is zero is calculated. The static erosion rate distribution in the specified cross section of the static magnetic field structure data is calculated based on the erosion rate of the erosion center line segment, the rotational erosion rate distribution caused along with rotation of the magnet is calculated, and the film formation rate distribution on the objective material is calculated by using the rotational erosion rate distribution.