Disclosed is a dry baker's yeast of a diploid, practical baker's yeast, which is obtained by mating an ATH1 and/or NTH1 gene-disrupted, haploid yeast as produced through gene manipulation of disrupting the ATH1 and/or NTH1 gene in an a-type haploid yeast of which the diploid is practical baker's yeast, with an ATH1 and/or NTH1 gene-disrupted, haploid yeast as produced through gene manipulation of disrupting the ATH1 and/or NTH1 gene in an &agr;-type haploid yeast of which the diploid is practical baker's yeast. The dry yeast does not require sugared water for its re-activation but can be rapidly re-activated only with water. Using the yeast, therefore, breads having good taste can be produced within a short period of time.