We investigated mating conditions about care temperature of queen before mating, mating period, and number of queen per mating cage to improve mating rate of Bombus terrestris. Among 19℃, 22℃ and 25℃, care temperatures of queen before mating, queen cared at 19℃ was more effective than those at 22℃ and 25℃ in death rate during care and mating periods, and colony development. In case of mating period, oviposition rate and preoviposition periods at queen mated during 3 days were 89.3% and 11.4 days, respectively, which was higher and earlier than those of queen mated during 5 days and 7 days. The rate of worker emergence, colony foundation and progeny-queen production at 3 days-mated queen were also 2.0-11.6% higher than those at queen mated during 5 days and 7 days. In number of queen per mating cage, the rate of worker emergence, colony foundation and progeny-queen production queen mated at mating cage with 10 queens and 30 males were 41.5%, 25.9% and 23.2%, respectively. These values correspond to 1.5-6.8 folds those queen mated at cage with 20 queens and 30 queens. Therefore, we supposed that care temperature favorable for B. terrestris queen was 19℃ and the period need to mating was 3 days, and the number of queen per mating cage (55×45×65 cm) was 10.