PURPOSE: To readily and inexpensively connect a panel with an end of a tank container, by forming a space defined by the panel, the end of the tank container and a working table, and charging a filling agent into this space.

CONSTITUTION: On the connection table 2 is placed the end 4 of the tank container with a resilient body 5 therebetween. A pressure plate 6 having a surface parallel to the panel 1 is lowered to push down the end 4 of the tank container and is engaged with the panel 1, and the lowering of the press plate is stopped when the panel 1 is firmly in contact with the connection table 2. By this operation, the panel 1 and the end 4 of the tank container are horizontally aligned in position, and the space 10 wherein the filling agent for connecting them will be introduced is defined by the panel 1, the end 4 of the tank container, the connection table 2 and the resilient body 5. Then the filling agent is introduced through a filling agent inlet 8 provided in the pressure plate 6 to fill the space 10. The pressure plate 6 is removed, and the connection table 2 is separated to obtain the connected product.