PROBLEM TO BE SOLVED: To provide a semiconductor device manufacturing method which can inhibit a dent from being formed on a surface of an encapsulation layer in a package.SOLUTION: In a semiconductor device manufacturing process, after forming an encapsulation film 17-1 in a temporary cured state by performing a series of processes including coating of a liquid encapsulation material 33 on a semiconductor wafer 21, defoaming and calcination, a series of processes including coating of the liquid encapsulation material 33, defoaming and final baking is performed again, and an encapsulation layer 17 forming an integrated layer without a borderline, which includes the encapsulation film 17-1 in the temporary cured state and an encapsulation film 17-2 composed of the encapsulation material 33 coated thereafter is formed. Accordingly, the encapsulation layer 17 having a uniform film thickness and a flat surface condition is formed.