PURPOSE: To stably execute continuous casting of a steel strip by standing rectangular thin metal sheets on one side surface of a flexible metal sheet in the equally closed pitch and connecting the flexible metal sheet in endless state as the inside of a mold.

CONSTITUTION: On one side surface of the flexible metal sheet 4, plural pieces of the L-shaped rectangular thin metal sheets 1 are stood in the longitudinal direction of the sheet 4 in the equally closed pitch (p) by fitting the end surface of a long side which a mold short side constituting part 3 is not arranged. The flexible metal sheet 4 is made to be the inside and the short side constituting part 3 in the mold is made to be the outside, and the sheet 4 is connected in the endless state to form the endless metal body 5. The endless metal body 5 is wound on a guide roll to constitute the strip continuous casting apparatus.