CROSSHEAD ENGINE

Provided is a crosshead engine that includes: a cylinder; a piston sliding in the cylinder; a piston rod (112a) having one end fixed to the piston; a crosshead (crosshead pin (114a)) connected to the other end side of the piston rod and reciprocating together with the piston; a connecting rod having one end supported by the crosshead; a crankshaft connected to the connecting rod and rotating in coordination with the reciprocation of both the piston and the crosshead; and a variable mechanism varies positions of top and bottom dead centers of the piston by changing a relative position between the piston rod and the crosshead in a stroke direction of the piston. The variable mechanism includes: a hydraulic pressure chamber (168a) which is provided in the crosshead and into which an end of the piston rod is inserted; and a hydraulic pressure adjustment mechanism which supplies hydraulic oil to the hydraulic pressure chamber or discharges the hydraulic oil from the hydraulic pressure chamber and which adjusts an entering position at which the end of the piston rod is inserted into the hydraulic pressure chamber in the stroke direction.