A semiconductor device which is capable of operating at an operation frequency “f”, includes a substrate, a first element unit and a second element unit. The substrate has a thermal diffusion coefficient “D”. The first element unit is formed on the substrate. The first element includes a first active element. The second element unit is adjacent to the first element unit on the substrate. The second element includes a second active element. The second active element acts on a different timing from the first active element. Moreover, a distance of between a first gravity center of the first element unit and a second gravity center of the second element unit is equal to or less than twice of a thermal diffusion length (D/πf)1/2.