The present disclosure suggests a locking device for containers. A locking device for containers according to an exemplary embodiment of the present disclosure includes: a housing including a base part, a protrusion protruded upwards from an upper surface of the base part, and a through hole formed by penetrating the base part and the protrusion in a vertical direction; a connection part rotatably inserted into the through hole of the housing; an upper cone positioned on the connection part and inserted into a lower corner fitting of a first container positioned on an upper end; and a lower cone positioned under the connection part and inserted into an upper corner fitting of a second container positioned on a lower end.