To provide a vehicular seat capable of ensuring the safety of a child by a simple action.

A recess part 4 capable of storing a child in a seated state is formed on a seat back 3 standing from a seat cushion 2. An auxiliary seat 5 which can be stored in the recess part 4 is supported so as to set up and fold down. A seat belt 7 is provided in the recess part 4. A child is seated in the recess part 4, and a seat belt 7 is laid on the child to ensure the safety of the child.