To provide a coating material concentration control system and method which can carry out concentration control of a coating material while controlling the level and the temperature in tanks.

A mixing tank mixes a raw solution and a diluting solution, and stores the resulting solution and discharges out of or feeds the solution to the next stage, and a supply tank mixes the solution from the mixing tank and the diluting solution, and stores the resulting solution, and feed the solution to a storage line or feed back the solution to the mixing tank. The sugar concentration, level, and temperature are measured individually and the supply, discharge, and feed-back are adjusted based on these measured values.