The present invention addresses the problem of providing a control system of a double-sided polishing device, a control device, and a method for producing a substrate with which it is possible to quickly control the flatness of a substrate with a high degree of precision by controlling polishing conditions. The present invention is a control system of a double-sided polishing device 10 that sandwiches a body W to be polished between an upper face plate 21 and a lower face plate 32 and that polishes a TOP surface 30a and a BOT surface 30b of the body W to be polished by causing the upper face plate and the lower face plate to rotate, wherein the control system is characterized in that: each of a TOP surface work amount PT (Ws) required in polishing of the TOP surface 30a, and a BOT surface work amount PB (Ws) required in polishing of the BOT surface 30b, are calculated; and polishing conditions are controlled so that the difference between the calculated TOP surface work amount PT and BOT surface work amount PB is kept within a prescribed range.