A synthesis gas production catalyst to be used for producing synthesis gas containing carbon monoxide and hydrogen from source gas containing methane-containing light hydrocarbons and carbon dioxide, wherein the catalyst comprises at least either one of the metals of ruthenium and rhodium carried on a carrier which contains magnesium oxide grains and calcium oxide existing on the surfaces of the magnesium oxide grains and shows a calcium oxide content between 0.005 mass % and 1.5 mass % in terms of Ca, and
- wherein the calcium oxide exists on the surfaces of the magnesium oxide grains by 0.05 mg-Ca/m2-MgO to 150 mg-Ca/m2-MgO in terms of Ca.