A vacuum pump is provided, which suppresses occurrence of a gas product in an exhaust side outlet of a thread groove and maintains pump performance over a long period. The vacuum pump includes inflow suppressing walls formed by widening greater an exhaust side end portion of ridge portions, extended along a gas exhaust direction on an outer circumferential surface of an inner circumference side stator, forward in a rotor rotating direction than an intake side end portion, the inflow suppressing walls suppressing retention of gas in exhaust side outlets of thread grooves engraved among the ridge portions.