A sheet material accumulating apparatus for accumulating a sheet material W into an accumulated bundle by arranging it in a mutually overlapping state is configured to be able to suppress an enlargement, a higher tallness, more complication, etc. of the apparatus and attain a curtailment of various costs, including a manufacture cost. The apparatus has a primary conveyer 2, a second conveyer 3, and an accumulation unit 4, the accumulation unit 4 has a posture conversion unit 35 for converting the sheet material W in a flatted posture into that in a standing posture, a descend conveyer unit 36 for conveying the sheet material W downward while keeping the standing posture, and a table top 7 for accumulating the received sheet material W sequentially while supporting it in a standup posture; the primary conveyer 2 has a flat conveyance plane 6 at a substantially same height as the table top 7; and the secondary conveyer 3 twists the sheet material W along a conveyance direction so that top and bottom thereof may be inverted while it is conveyed in a rise inclined direction.