To provide a bag body with an opening and closing device, which can be opened and closed with a hand, and a bag body with an opening and closing tool having a synthetic resin-made zipper or a hook-and-loop fastener mounted on the bag body with the opening and closing device.

The opening part 6 of the bag body 5 is composed of two sides 1 and 2 and two intersecting points 3 and 4. The bag body 5 has: the opening and closing tool 18 composed of a plate-like body 19 straight line parts 8, 9, 46 and 47; connecting lines 14, 15, 16 and 17 formed by connecting points 10, 11, 12 and 13 to connecting points 20, 21, 22 and 23 respectively; support parts 44, 48, 49 and 50 comprising connecting lines 14, 15, 16 and 17 and straight line parts 8, 46, 9 and 47; and the first hinges 29 and 30 swingably integrally mounted around the center of the laminated face-to-face arranged connecting points 20, 21, 22 and 23 to each other, the first hinges 29 and 30 being symmetrical about the center 45 of the central part 7 of the opening 6.