Fifteen others were injured and three are serious, the Chitwan Police said.
The accident took place when the Ba 2 Kha 5985 bus tried to overtake other vehicle heading for Kathmandu from Narayangadh. The deceased woman aged about 27 years has not been identified so far.
Three injured are undergoing treatment in Chitwan Medical College and the rest in various hospitals of Chitwan, police said.
Road accident in Sarlahi claims a life, one injured