An air guide structure for a saddle type vehicle for reducing the influence of a negative pressure on a rider. In an air guide structure for a motorcycle wherein a windscreen for the protection against air is provided on a front cover provided at a front portion of a vehicle body such that air is guided to the rear of the windscreen on the vehicle body to reduce a negative pressure to be generated behind the windscreen, an inlet port is provided between a central portion of a front end of the windscreen and the front cover. Further, a stepped portion that is formed stepwise in the forward and backward direction on an upper face of the front cover in the inside of the inlet port is provided, and a sectoral recessed portion is provided at a central portion of the stepped portion in the vehicle widthwise direction.