The play behaviors in relation to the behavioral development among a group of 15 vampire bats Desmodus rotundus (eight adults and seven young) were observed in captivity. Solitary and social plays occurred mainly in the young. In the solitary plays (exploration), the activities reached the peak at the age of 1 year and decreased gradually to the age of 2 - 3 years. The social plays including chasing, jostling and wrestling appeared largely in young bats. The central role of the social plays was taken by young and subadult males (the ages of 3 to 21 months) . Especially they had favorite play partners. The behaviors of young may contribute to maintain the social stability in this species.