There is provided a method of manufacturing a semiconductor device, in which removal of the resist after ion implantation becomes easy. In order to solve the above problem, the manufacturing method includes a step of removing a resist mask after a step of implanting an ion of a rare gas element. Also, another manufacturing method includes a first step of implanting an ion of an impurity element for imparting a conductivity type, a second step of implanting an ion of a rare gas element, and a third step of removing a resist mask after the first step and the second step.