A bulking apparatus (1) includes a hot air generator, an air supply duct (2) having an inlet (21) for receiving hot air and an outlet (22) for delivering the hot air to nonwoven fabric, and a sucking part (31) sucking in hot air delivered from the outlet (22) and passed through nonwoven fabric (10) to increase the bulk of the nonwoven fabric being transported. The air supply duct (2) has an inflow portion (24) leading the hot air introduced into the inlet (21) to flow in parallel to the transverse direction of the nonwoven fabric and an outflow portion (25) forming an angle with the inflow portion (24) to lead the hot air flowing through the inflow portion to the outlet (22). The air supply duct (2) has a plurality of baffle plates (26) disposed therein, each baffle plate having a flow-facing part (26A) and a flow-guiding part (26B) located in the inflow portion (24) and the outflow portion (25), respectively. The baffle plates (26), are arranged such that the inflow path (24A) in the inflow portion (24) has a decreasing cross-sectional area with distance from the inlet (21).
