To realize smooth production by preventing any situation that products whose man-hours are large are likely to be in short supply, and maintaining the leveling of the loads of the production line.

In this production method for a mixed flow production line for continuously producing first products to be mass produced and second products to be produced in a low volume in a mixed flow state for periodically shipping those products corresponding to each requested shipping quantity, the maximum quantity of the first and second products occupying the shipping quantity each time in the past relatively long period is held as each minimum stock quantity, and normally only the first products are produced. Just after the second products are shipped in not less than one lot from the minimum stock quantity, the second products are produced by interrupting the first products in order to supply the number of shipping lots by lot units.