The invention relates to an automobile seat which comprises a cushion and a backrest. The backrest comprises a main body portion in the middle and side body portions arranged on two sides of the main body portion. The main body portion comprises a first main body with a lower side portion connected with a rear side portion of the cushion in a rotation mode and a second main body with a lower side portion connected with an upper side portion of the first main body in a rotation mode. The side body portions comprise a first side body with a lower side portion connected with a rear side portion of the cushion fixedly and a second side body with a lower side portion connected with an upper side portion of the first side body in a rotation mode. The backrest has two working states. When the backrest is in the first working state, the first main body, the second main body, the first side body and the second side body are gathered to form an integrated structure, and at this time users can lean against the backrest. When the backrest is in the second working state, the first main body is folded forwards to press the cushion. At this time, the first main body, the second main body, the first side body and the second side body form a child seat for children. The automobile seat is dual-purpose and can be used by adults and the children.