IC CARD

PROBLEM TO BE SOLVED: To improve the fusion strength between the upper and lower panels by applying the ultrasonic vibrations to the upper panel in a state in which a linear projecting part is fitted into a groove part and filling up this groove part with the fused projecting part to fuse both panels together. SOLUTION: A rib 33b serving as a projecting part having a triangular section is linearly formed along the outer circumference of an upper frame 32 of an upper case 30. Then a groove-shaped rib holding part 43b is linearly formed along the outer circumference of a lower frame 42 of a lower case 40 that is placed opposite to the case 30. Then the case 30 is pressed and at the same time the ultrasonic vibrations are vertically applied to the case 30. Thus, the heat is generated by friction between the rib 33b and the part 43b to fuse the tip part of the rib 33b and the surface of the part 43b. Then the ultrasonic vibrations are stopped before the frame 32 excluding the rib 33b touches the frame 42, and the fused part is cooled. Thus, the tip part of the rib 33b is fused to the part 43b and an IC card is completed.