A sorter for sorting sheets successively supplied thereto, comprising: a fixed frame; a movable frame movable vertically with respect to the fixed frame; a plurality of bins arranged one over another at a predetermined distance and each having an upper surface sloping upwardly in a sheet supply direction for receiving thereon one or more of the sheets, the bins being supported on the movable frame; a non-sort bin situated upwardly of the bins and supported pivotally on an upper portion of the movable frame for receiving the non-sorted sheets, the non-sort bin being biased normally so as to slant upwardly in the sheet supply direction; and a holder mounted on the fixed frame, at a position to which the sheets are to be supplied, for holding the non-sorer bin horizontally against the bias.