Abstract: A mold degassing device which can reduce the likelihood of particulates entering between a valve stem and an insertion hole is provided. The mold degassing device (10, 40, 50) includes an inflow passage (11, 41, 51), a discharge passage (12), a communication passage (13), a valve device (30) for opening and closing the communication passage (13), a gas-flow adjusting part to adjust a gas flow. A wall surface forming the communication passage (13) is provided with an insertion hole (32d) through which a valve stem (31) of the valve device (30) is inserted. The gas-flow adjusting part is positioned closer to the inflow passage (11, 41, 51) than the insertion hole (32d) and, when gas is discharged, generates a gas flow directed rotationally about an axis (C).