Switching element unit

A switching element unit comprising:

• a switching element;
• and
• a smoothing capacitor that suppresses variation in DC voltage to be supplied to the switching element, wherein
• the smoothing capacitor includes positive electrode-side internal electrodes and negative electrode-side internal electrodes alternatively arranged in a stacking direction,
• dielectric portions are stacked in the stacking direction with the positive electrode-side internal electrodes and the negative electrode-side internal electrodes interposed therebetween,
• an element mounting surface formed in an outer surface of the smoothing capacitor is formed integrally with the dielectric portions,
• a capacitor connection electrode as an electrode that is electrically connected to a terminal of the smoothing capacitor is formed on the element mounting surface,
• the switching element is placed on the element mounting surface such that a main terminal of the switching element is electrically connected to the capacitor connection electrode, and
• the switching element has an opposing mounting surface facing the element mounting surface,
• the switching element is placed on the element mounting surface so that the opposing mounting surface contacts the element mounting surface directly or via a bonding member, and
• the switching element includes on the opposing mounting surface the main terminal that is electrically connected to a supply source of the DC voltage.