A conveying roller unit comprises a first unit, a second unit, and a lock mechanism. The first unit comprises: a roller section; and a hollow cylindrical holder section. The second unit can be removably mounted to the first unit, and comprises: a second connection section; a rod section inserted into the holder section. The lock mechanism includes: a first engagement section provided on the inner circumferential surface of the holder section; a second engagement section provided on the outer circumferential surface of the rod section; and a urging member for pressing the second unit in the direction in which the rod section comes out of the holder section. The urging member maintains the first engagement section and the second engagement section in an engaged state and restricts the position of the second unit relative to the first unit in both the circumferential direction and the rotation axis direction.