a first supply unit that supplies a raw material gas comprising methane and carbon dioxide;

a synthesis gas production unit that comprises a first catalyst structure, receives supply of the raw material gas from the first supply unit, and produces a synthesis gas comprising carbon monoxide and hydrogen from methane and carbon dioxide in the raw material gas while heating the first catalyst structure;

a second supply unit that supplies the synthesis gas discharged from the synthesis gas production unit;

a hydrocarbon production unit that comprises a second catalyst structure, receives supply of the synthesis gas from the second supply unit, and produces, from carbon monoxide and hydrogen in the synthesis gas, hydrocarbons including lower olefins including propylene and aromatic hydrocarbons having six or more and ten or less carbon atoms while heating the second catalyst structure; and

a first detection unit that detects propylene and the aromatic hydrocarbons in the hydrocarbons discharged from the hydrocarbon production unit, wherein

the first catalyst structure includes first supports each having a porous structure and including a zeolite-type compound, and at least one first catalytic material present in the first supports,

the first supports have first channels communicating with outside the first supports,

the first catalytic material is in the form of first metal fine particle and is present at least in the first channels of the first supports,

the second catalyst structure includes second supports each having a porous structure and including a zeolite-type compound, and at least one second metal fine particle present in the second supports,

the second supports have second channels communicating with outside the second supports, and

some of the second channels have an average inner diameter of 0.95 nm or less.