An electrochemical reduction device 10 is provided with an electrode unit 100, a power control unit 20, an organic material storage tank 30, a water storage tank 40, a gas-liquid separator 50, and a control unit 60. The electrode unit 100 has an electrolyte membrane 110, a reduction electrode 120, and an oxygen evolving electrode 130. The electrolyte membrane 110 is formed of an ionomer. A reduction catalyst used for the reduction electrode 120 contains at least one of Pt and Pd. The oxygen evolving electrode 130 contains catalysts of noble metal oxides such as RuO 2 , IrO 2 , and the like. The control unit 60 controls the power control unit 20 such that a relationship, V HER - 20 mV ‰¤ V CA - V TRR , can be satisfied when the potential at a reversible hydrogen electrode, the standard redox potential of an aromatic hydrocarbon compound or an N-containing heterocyclic aromatic compound, and the potential of the reduction electrode 120 are expressed as V HER , V TRR , and V CA , respectively.
