To provide a sliding type single opening two door device having an inner door and an outer door movable in the width direction which is low-cost, excellent in operability, and high in coolant leakage preventing effect.

An outer door fixing piece 13 extended upward from the upper edge is provided in the outer door 4, an inner door fixing piece 14 extended inward from the upper edge is provided in the inner door 5, outer door guide mechanisms 7, 8 are attached inside a device body cover 1, an outer door suspension member 12 is attached to the outer door guide mechanisms 7, 8, the outer door fixing piece 13 is attached to the lower end of the outer door suspension member 12 to suspend the outer door 4, inner door guiding mechanisms 9, 10 are attached inside the outer door suspension member 12, an inner door suspension member 15 extended downward is attached to the inner door guiding mechanisms 9, 10, the inner door fixing piece 14 is attached to the lower end of the inner door suspension member 15 to suspend the inner door 4, and a flexible sheet material 16 is provided inside a space A surrounded by the upper face of the inner door 5, the outer door fixing piece 13, the inner door suspension member 15, and the inner door guiding mechanisms 9, 10 when both doors are opened and the inner door 5 and the outer door 4 overlap.