Friction reducing units are integrally configured in a tensioner arm and a chain guide that are disposed at both sides of a timing chain to make contact with the timing chain, respectively to increase the thickness of the oil film, such that it is possible to improve durability of an entire timing chain system while preventing noise from being generated by reducing a friction loss generated on each of contact surfaces of the tensioner arm and the chain guide and prevent fuel efficiency of the vehicle from being deteriorated.Provided is a friction reducing device of a timing chain for a vehicle in a timing chain system including a tensioner arm and a chain guide disposed at both sides of a timing chain interconnecting a crank sprocket mounted a crank shaft and a cam sprocket mounted on the cam shaft so as to transfer a rotational force of the crank shaft to a cam shaft, respectively to prevent the timing chain from being separated while reducing vibration of the timing chain, wherein the tensioner arm and the chain guide further include first and second friction reducing units integrally formed, respectively in order to reduce a friction loss by increasing the thickness of an oil film between each of contact surfaces that make sliding-contact with the timing chain.