The pillow of the present disclosure comprises: a first unit body and a second unit body which are arranged side by side in the left and right directions and are connected to each other with a variable gap therebetween； a third unit body which is coupled to the first unit body so as to move relative thereto in the forward and backward directions； a fourth unit body which is coupled to the second unit body so as to move relative thereto in the forward and backward directions, disposed in parallel to the third unit body in the left and right directions and coupled thereto with a variable gap therebetween； a first gap adjusting unit for allowing the third unit body and the fourth unit body to get further apart from or closer to each other in the forward and backward directions with respect to the first unit body and the second unit body； and a second gap adjusting unit for allowing the first unit body and the third unit body to get further apart from or closer to each other in the left and right directions with respect to the second unit body and the fourth unit body.
