To provide a synthetic resin bag body with a slider for securing a water tightness and for putting in an item to be enclosed or taking out the item easily.

This synthetic resin bag body comprises front and back two body films whose right and left are side-sealed. The opening of the bag body is provided with a male/female engaging type zipper openable by a slider. An inside guide 6 provided on the slider 5 for opening the zipper 4 is formed slantingly in the closing direction of the zipper 4 at the center of the slider 5 moving direction. The closing end 4a of the zipper 4 is formed with an upward inclining guide 7 and the guide 7 pulls up the slider 5 for removing the guide 6 from the zipper 4 at the closing end 4a of the zipper 4.