Provided are a glass substrate for an information recording medium, which has both high strength and high flatness and can be manufactured at low cost, a method for manufacturing such glass substrate and an information recording medium using such glass substrate. The glass substrate for the information recording medium satisfies inequalities of 0.1.ltoreq.(W1-W3)/W2.ltoreq.5, where, W1 is an ion concentration at the center portion in the thickness direction of the glass substrate in a chemically reinforced region at the outer circumference end surface and the inner circumference end surface of the glass substrate and is the maximum value of K.sup.+ ion concentration, W2 is a Na.sup.+ ion concentration at a position where the K.sup.+ ion concentration is maximum, and W3 is a K.sup.+ ion concentration in a glass substrate region not chemically reinforced.