A solid electrolytic capacitor includes a capacitor element having two opposite cathode surfaces, a cathode terminal metal plate having a first cathode connecting portion electrically connected to one of the two opposite cathode surfaces, and an auxiliary cathode metal plate having a second cathode connecting portion electrically connected to the other one of the two opposite cathode surfaces of the capacitor element. The cathode terminal metal plate includes a groove electrically connected to the first cathode connecting portion. The auxiliary cathode metal plate includes an end portion that is electrically connected to the second cathode connecting portion and engages with the groove. The cathode terminal metal plate further includes an outer terminal portion.