A semiconductor device configures one arm of an upper-lower arm circuit, and includes: a semiconductor element that includes a first main electrode and a second main electrode, wherein a main current between the first main electrode and the second main electrode; and multiple main terminals that include a first main terminal connected to the first main electrode and a second main terminal connected to the second main electrode. The first main terminal and the second main terminal are placed adjacent to each other; A lateral surface of the first main terminal and a lateral surface of the second main terminal face each other in one direction orthogonal to a thickness direction of the semiconductor element.