A semiconductor device, including a plurality of semiconductor modules, each including a semiconductor element, a main terminal and a wiring portion that connects the semiconductor element and the main terminal, and at least one busbar that each includes a terminal portion, and a plurality of attachment portions, the attachment portions being respectively connected to the main terminals of the semiconductor modules, such that the at least one busbar connects the semiconductor modules in parallel. The largest resistance among all resistances between the terminal portion and each of the attachment portions in each busbar is 10% or less of a resistance of the wiring portion in each semiconductor module. The largest inductance among all inductances between the terminal portion and each of the attachment portions in each busbar is 10% or less of an inductance of the wiring portion in each semiconductor module.