A demolding method, comprising the steps of: placing a tight-flask cope on a tight-flask drag for mating, such that a gate for the tight-flask cope and drag faces upward, and after the mated tight-flask cope and drag are poured with molten metal, transferring the mated tight-flask cope and drag placed on a lower level truck to a level-truck-mounting station; placing an upper level truck on the tight-flask cope and drag at the level-truck-mounting station such that the upper level truck faces the lower level truck; transferring the tight-flask cope and drag and the lower and upper level trucks (9, 10) from the level-truck-mounting station to a reversing station; reversing the tight-flask cope and drag and the upper and lower level trucks (9, 10) at the reversing station with the tight-flask cope and drag being sandwiched between the upper level truck and the lower level truck so that the upwardly facing gate faces downward; transferring the reversed tight-flask cope and drag and upper and lower level trucks (9; 10) from the reversing station to a level-truck-separating station; separating at the level-truck-separating station the lower level truck, which has been reversed and thus located above; returning the separated lower level truck to the level-truck-mounting station, and placing the returned lower level truck as an upper level truck on a tight-flask cope that is transferred together with a mated tight-flask drag to the level-truck-mounting station; separating the upper level truck from an assembly of the tight-flask cope and drag and the upper level truck, which assembly has been transferred from the level-truck-separating station; and drawing at least a cope, and an as-cast product from the tight-flask cope and drag, with the gate facing downward, from above to below, wherein at the step of drawing a drag is drawn at the same time that the cope and the as-cast product are drawn, or before the step of drawing, separating the tight-flask drag, which is located above, from the tight-flask cope, which has been reversed and thus located under the tight-flask drag, allowing an as-cast product to remain in the tight-flask cope. placing a tight-flask cope on a tight-flask drag for mating, such that a gate for the tight-flask cope and drag faces upward, and after the mated tight-flask cope and drag are poured with molten metal, transferring the mated tight-flask cope and drag placed on a lower level truck to a level-truck-mounting station; placing an upper level truck on the tight-flask cope and drag at the level-truck-mounting station such that the upper level truck faces the lower level truck; transferring the tight-flask cope and drag and the lower and upper level trucks (9, 10) from the level-truck-mounting station to a reversing station; reversing the tight-flask cope and drag and the upper and lower level trucks (9, 10) at the reversing station with the tight-flask cope and drag being sandwiched between the upper level truck and the lower level truck so that the upwardly facing gate faces downward; transferring the reversed tight-flask cope and drag and upper and lower level trucks (9; 10) from the reversing station to a level-truck-separating station; separating at the level-truck-separating station the lower level truck, which has been reversed and thus located above; returning the separated lower level truck to the level-truck-mounting station, and placing the returned lower level truck as an upper level truck on a tight-flask cope that is transferred together with a mated tight-flask drag to the level-truck-mounting station; separating the upper level truck from an assembly of the tight-flask cope and drag and the upper level truck, which assembly has been transferred from the level-truck-separating station; and drawing at least a cope, and an as-cast product from the tight-flask cope and drag, with the gate facing downward, from above to below, wherein at the step of drawing a drag is drawn at the same time that the cope and the as-cast product are drawn, or before the step of drawing, separating the tight-flask drag, which is located above, from the tight-flask cope, which has been reversed and thus located under the tight-flask drag, allowing an as-cast product to remain in the tight-flask cope.