The present invention relates to beta-glucosidase that is mutated to have enhanced activity, and a method for producing bioethanol using the same. More particularly, the present invention relates to a polynucleotide encoding beta-glucosidase that is mutated to have enhanced activity, beta-glucosidase expressed from the polynucleotide, an expression vector including the polynucleotide, a transformant that is transformed with the expression vector, a method for producing the mutated beta-glucosidase using the transformant, and a method for producing bioethanol using the transformant. The mutant beta-glucosidase of the present invention increases production of glucose much more than the conventional beta-glucosidase, and thus it can be widely used for economic production of bioethanol.