A tread forming step of forming a non-conductive tread rubber includes a first step of forming the tread rubber in such a manner that a shoulder portion becomes smaller in diameter than a finish cross sectional shape, a second step of setting up a conductive layer extending along a tire circumferential direction while alternately passing through a first position which is exposed to a tread surface of the shoulder portion, and a second position which comes into contact with a sidewall rubber in an outer side in a tire width direction than the first position, and a third step forming a finish cross sectional shape of the tread rubber by adding a non-conductive rubber to the shoulder portion of the tread rubber.