A capacitor unit includes a capacitor having a positive electrode and a negative electrode, a positive bus bar, a negative bus bar, a sealing resin, an insulator. The positive bus bar and the negative bus bar are respectively connected to the positive electrode and the negative electrode. The sealing resin seals the capacitor, a part of the positive bus bar, and a part of the negative bus bar. The insulator is located between the positive bus bar and the negative bus bar. The insulator includes a recess recessed from either surface of the insulator facing the positive bus bar or the negative bus bar. At least a part of the recess is exposed from the sealing resin.