We synthesized a dithiolato-bridged heterometal trinuclear complex [{(η5-C5Me5)Rh(S2C6H4)}2Mo(CO)2] (1) in which two rhodadithiolene complex units are bridged by a Mo(CO)2 moiety. Complex 1 with a RhIII−Mo0−RhIII bond exhibits reversible one-step two-electron reduction with potential inversion. This redox process between 1 and 12− accompanies a reversible structural change, which is an alternation in the CO coordination mode between semibridging and bridging. The ground state of dianion 12− with a RhII−Mo0−RhII bond is assigned to spin triplet. These alternations of CO coordination mode and spin state are fully consistent with the density functional theory calculation results. This is the first example of multinuclear metalladithiolene complex which was successful in elucidating a reversible multielectron redox process associated with structural change and spin state change.