A robotic surgical instrument according to an embodiment may include: an end effector; a first support body that supports the end effector rotatably about a first shaft; a second support body that supports the first support body rotatably about a second shaft; an elongated element to rotate the first support body with respect to the second support body; and a shaft to which the second support body is connected. The elongated element includes a wire, an attachment fixed to the wire, and a protection tube fixed to the wire. The first support body includes a through-hole having a size in which the attachment and the protection tube are insertable.