This paper presents a general method of stress analysis of cracked wide plates subjected to plane stresses at infinity. Geometric and other parameters may be arbitrarily specified, including the number, locations, directions and lengths of the cracks as well as the stress parameters. The stress function is first assumed as the sum of stress functions having singulariteies within the cracks and at infinity, and the unknown parameters are determined from the boundary conditions using a perturbation technique. Then the stress intensity factors at all the crack tips are given by power series formulae, and they are considered to give practivaly exact values so far as the enclosing circles of all the cracks are not so close to each other. Numerical examples are given for several typical cases of practical importance.