A breather device for an engine, comprising: a valve holder ; and a breather valve supported by the valve holder , wherein the valve holder includes: a holder body having a valve port of the breather valve ; an outlet passage pipe formed of metal and having a blow-by gas outlet passage formed inside, the blow-by gas outlet passage communicating with the valve port and being located below the valve port ; and a heater that heats the outlet passage pipe , an outer peripheral surface of the outlet passage pipe is wrapped with the holder body formed of a material having lower thermal conductivity than that of the outlet passage pipe , the holder body has a heater insertion port , and the heater is inserted from the heater insertion port toward a heat input wall of the outlet passage pipe , wherein the outlet passage pipe includes: a pipe start end wall closing a pipe start end; a communication port provided in the pipe upper wall near the pipe start end and communicating with the valve port ; and a pipe terminal peripheral wall having a pipe outlet opened at the opposite end of the pipe start end wall , and the pipe start end wall is the heat input wall of the outlet passage pipe , characterised in that the holder body has a downward hole that connects the valve port and the communication port located below the valve port , the communication port is formed downward in series with the downward hole , the blow-by gas outlet passage faces in a front-back direction substantially perpendicular to a direction of the communication port below the communication port , when a back side is defined to be one side in the front-back direction, the heat input wall is disposed at a back end of the blow-by gas outlet passage , and the heater is inserted toward the heat input wall from the back side. a valve holder ; and a breather valve supported by the valve holder , wherein the valve holder includes: a holder body having a valve port of the breather valve ; an outlet passage pipe formed of metal and having a blow-by gas outlet passage formed inside, the blow-by gas outlet passage communicating with the valve port and being located below the valve port ; and a heater that heats the outlet passage pipe , an outer peripheral surface of the outlet passage pipe is wrapped with the holder body formed of a material having lower thermal conductivity than that of the outlet passage pipe , the holder body has a heater insertion port , and the heater is inserted from the heater insertion port toward a heat input wall of the outlet passage pipe , wherein the outlet passage pipe includes: a pipe start end wall closing a pipe start end; a communication port provided in the pipe upper wall near the pipe start end and communicating with the valve port ; and a pipe terminal peripheral wall having a pipe outlet opened at the opposite end of the pipe start end wall , and the pipe start end wall is the heat input wall of the outlet passage pipe , characterised in that the holder body has a downward hole that connects the valve port and the communication port located below the valve port , the communication port is formed downward in series with the downward hole , the blow-by gas outlet passage faces in a front-back direction substantially perpendicular to a direction of the communication port below the communication port , when a back side is defined to be one side in the front-back direction, the heat input wall is disposed at a back end of the blow-by gas outlet passage , and the heater is inserted toward the heat input wall from the back side. <EOS>