A method and apparatus for performing treatment of substrates with a treating liquid. A first storage unit stores an initial life count specifying an allowable number of treatments of substrates to be carried out with treating liquid after an entire liquid replacement with a new supply of the treating liquid; a second storage device stores a normal life count specifying an allowable number of treatments to be carried out with the treating liquid after reaching the initial life count and after a partial liquid replacement; and a control device repeats treatment of the substrates after the entire liquid replacement until the initial life count is reached; and after the initial life count has been reached and the partial liquid replacement has been made, repeats treatment of the substrates until the normal life count is reached, and makes the partial liquid replacement each succeeding time the normal life count is reached.