"We can tell a baby's health condition by listening to the way they cry. Today she may get nervous and not cry so much, but I want to hear her healthy crying," Hisae Watanabe, mother of an eight-month-old, told AFP.
The "crying sumo" is held at shrines and temples nationwide, to the delight of parents and onlookers.
Shigemi Fuji, chairman of Asakusa Tourism Federation which organised the event, said some people might think it's terrible they make babies cry.