Disclosed is a method of manufacturing a circuit board comprising an insulating substrate and a conductor pattern of a low resistivity which can be prevented from being peeled off the substrate by a thermal stress. The method comprises the step of forming an insulating layer on an insulating substrate, the insulating layer being provided with a groove having a depth of at least 20 .mu.m and shaped like a conductor pattern which is to be formed later, the step of filling the groove of the insulating layer with a paste composition consisting of a powdery material capable of forming an electrically conductive metal, a fine particles having a thermal expansion coefficient smaller than that of the electrically conductive metal, the fine particles being used in an amount of 0.5 to 20% by volume based on the amount of the electrically conductive metal, and an organic binder, and the step of baking the paste composition so as to form a conductor pattern on the insulating substrate, the conductor pattern containing as a main component the electrically conductive metal and the fine particles having a thermal expansion coefficient smaller than that of the metal, the fine particles being dispersed in the electrically conductive metal in an amount of 0.5 to 20% by volume based on the amount of the electrically conductive metal.