A valve timing adjustment device includes: a first rotatable body that is rotated about a rotational axis synchronously with one of a drive shaft and a driven shaft of an engine; and a second rotatable body that is rotated about the rotational axis synchronously with the other one of the drive shaft and the driven shaft. The first rotatable body includes: a fastening portion, a slide portion and a bearing portion. The fastening portion is fastened to the one of the drive shaft and the driven shaft. The bearing portion includes an outer peripheral surface that is opposed to an inner peripheral surface of the second rotatable body, and the bearing portion rotatably supports the second rotatable body. The fastening portion projects on one axial side of the slide portion and the bearing portion in an axial direction toward the one of the drive shaft and the driven shaft.