To provide a transfer line device reducing an evaporation rate of a refrigerant even in an operation in a state that a dewar-side transfer line is constantly inserted.

This transfer line device including a container-side transfer line inserted to a container storing a refrigerant at its one end and composed of a double-pipe, the dewar-side transfer line inserted to a dewar at its one end and composed of a double-pipe, and a bayonet connecting the other end of the container-side transfer line and the other end of the dewar-side transfer line, further includes an evaporation reducing means disposed in an inner pipe of the double-pipe at the other end of the dewar-side transfer line for reducing the amount of evaporation of the refrigerant.