PURPOSE: To positively being the ratio of charging works into an assembling line close to a production target when a production target is changed by charging vehicle works into the assembling line so as to bring them close to a set ratio which is previously set.

CONSTITUTION: Vehicle works 12 for satisfying a work charging condition are extracted from vehicle works 12 in a storage 16. When a plurality of proposed vehicle works are extracted, the ratio in the storage concerning respective restraint conditions are computed. When the ratio in the storage is within a set range, the vehicle works are selected by a set ratio condition, and when the ratio is beyond the range, the vehicle works 12 are selected by a ratio preference condition. When the proposed vehicle work is one, the vehicle work 12 becomes the charging vehicle work.