A method of hydrolysis of cellulose uses a filamentous fungus-derived cellulase as a carbohydrase and includes adding the carbohydrase to cellulose to perform primary hydrolysis and then subjecting the primary hydrolysate to solid-liquid separation into a primary sugar liquid and solids; adding water to the solids and performing secondary hydrolysis, followed by subjecting the secondary hydrolysate to solid-liquid separation into a secondary sugar liquid and a residue; and filtering the primary sugar liquid and/or secondary sugar liquid through an ultrafiltration membrane, and recovering the carbohydrase from the feed side and recovering a sugar solution from the permeate side.