An electric circuit apparatus includes: a first-circuit board that includes a first-through-hole, and a first-electrode disposed on a front side of the first-circuit-board; a second-circuit-board that is disposed on a back side of the first-circuit-board, the second-circuit-board including on the front side of the second-circuit-board a second-electrode associated with the first-through-hole; a semiconductor device that is disposed on the front side of the first-circuit-board, the semiconductor device including on a back side a third-electrode-associated with the first-electrode, and a fourth-electrode-associated with the second-electrode; a first-bonding-material that bonds the first-electrode and the-third-electrode; a second-bonding-material that bonds the second-electrode and the fourth-electrode while passing through the first-through-hole; and a support body that is disposed between the first-electrode and the second-circuit-board and that supports the first-circuit-board.