1. A simulation method, comprising: acquiring a processing condition for performing predetermined processing on a processing target with use of plasma; calculating a solid angle corresponding to a field-of-view region through which plasma space is viewable from a predetermined evaluation point in the predetermined evaluation point on a surface of the processing target based on the processing condition; and calculating an incident radical amount entering the evaluation point by a flux method with use of a function which takes a reaction probability between the solid angle and the evaluation point of a radical entering the evaluation point as an argument.