RECIPROCATING ENGINE

A reciprocating engine has a piston which reciprocates in a cylinder due to explosion pressure produced in a combustion chamber (124) formed in the cylinder (110). The reciprocating engine includes: a liquid fuel supply unit (148) that supplies a liquid fuel to the combustion chamber; and a gas supply unit (a fuel gas supply unit (150) and an EGR supply unit (152)) that supplies, into the cylinder, fuel gas and EGR gas as exhaust gas which is produced from combustion in the combustion chamber and is discharged from the combustion chamber.