A design method of a spectacle lens, includes: measuring an angle formed by a direction of a head of a person seeing the front without lens and a direction of the head of the person seeing an object located in a direction angled to the front direction of the person without lens to calculate a visual action index Mn according to the following equation (1) as an initial value; temporarily designing a spectacle lens based on the visual action index; and simulating visual action of the person wearing the temporarily designed spectacle lens and correcting the visual action index based on the simulation result M n = β n α n ( 1 ) wherein αn is an angle formed by the front direction of the person and a direction in which the object actually exists, βn is a rotation angle of the head of the person seeing the object without lens, and n represents the object.