Abstract: There is provided a container/closure lock device that is safe, simple and down-sized with a reduced number of components and can be manufactured at reduced cost. A container is provided with brackets 14a through 14f for receiving the wall of a closure, each of said brackets 14a through 14f being provided with a through bore 17 bored through its arm 16. Pin holders 19a through 19f having respective channels 22 are fitted to the respective outer surfaces of the corresponding brackets 14a through 14f, the through bores 17 and the corresponding channels 22 being aligned respectively. Lock pins 26a through 26f are respectively inserted into and held to the corresponding channels 22. A rotary ring 29 provided with slots 30a through 30f is fitted to the outer peripheral surface of the container 11 in such a way that the slots 30a through 30f respectively intersect the corresponding lock pins 26a through 26f.