There is provided an improved vial lid fastening device capable of reliably completing lid fastening in a short time. The vial lid fastening device 30 has a lid rotating device 51, a lid placing member 52, 53, a transporting device 55, 56, a first lid body reservoir 115, 116, a vial lid holding and supplying device 57, and a vial discharging device 58. A lid body 3 slides on an inclined flat surface 102 to reach a terminal mechanism part 101, and a stepped section 31 of the lid body 3 engages a stepped section holder 105. The lid body 3 is grasped by chuck claws 35 and is rotated as engaged to the terminal mechanism part 101 of the stepped section holder 105. Then, one of rotation regulating protrusions 28a, 28b of the lid body 3 is allowed to collide with a rotation preventing member 107 of the lid placing member 52. Thus, position determination in a rotation direction is performed with reference to the rotation regulating projections 28a, 28b and such position is maintained fixedly. Thereafter, the lid body 3 is mated with the vial body 2 and then rotated by a chuck.