An emergency staircase includes a plurality of step forming members that are housed in a casing. A podium and a railing are fitted to the casing so that the podium and the railing can be unfolded against the casing. Each of the step forming members includes a pair of guiding parts which are arranged in parallel, and a step plate that is sandwiched between the guiding parts of each pair and fastened to each of the guiding parts, so that left and right pairs of resulting squarish U-shapes face each other. Inner guiding parts and outer guiding parts are mutually of a similar configuration, so that each inner one is relatively smaller than each outer one by the thickness of the part. The protrusions act as sliding contacts between adjacent guiding parts.