There is provided a blowby gas atmosphere releasing device 20 for an engine 1 in which an intake flow path 3 is disposed at one side of an engine body 2 and an exhaust flow path 4 is disposed at the other side. The blowby gas atmosphere releasing device 20 includes an oil separator 22 that is connected to the engine body 2 and separates oil contained in blowby gas, and an atmosphere releasing pipe 23 that is connected to the oil separator 22 and is used to release the blowby gas to the atmosphere. The atmosphere releasing pipe 23 is disposed along the other side of the engine body 2.