noun
pellet drum; rattle drum
A small traditional Japanese drum with two beads on strings that strike the drumheads when the handle is twisted. Commonly used as a children's toy.
子どもがでんでん太鼓を振って遊んでいる。
The child is playing with a pellet drum, shaking it.
The name is onomatopoeic, from the sound 'den-den' made by the beads hitting the drum. The exact historical origin is uncertain.