There is disclosed a non-coated base fabric for air bag characterized in that maximum value of inner pressure of a woven fabric in measurement of dynamic air permeability at 50 to 65° C. is 70 to 100 kpa and biaxial strain rate of the base fabric at that time is 2.9 to 4.0%. Preferably, a yarn which constitutes the woven fabric is Nylon 66 fiber, content of an oil component remaining in the woven fabric is 0.04 to 0.60% by weight to the woven fabric, main ingredient of the oil component is an olefin type polymer having a melting point of 60° C. or lower, and the woven fabric contains 20 to 200 ppm of a phosphorus component.