A valve timing adjusting device includes: a first rotary body which rotates in synchronization with one of a crankshaft and a camshaft and into which lubricating fluid is supplied; a second rotary body which rotates in synchronization with the other; a torque producing unit for producing control torque; and a phase change unit including a planetary gear mechanism in which a planetary gear is engaged with a sun gear in such a way as to be able to perform a planetary motion. The phase change unit changes a relative rotational phase between the first rotary body and the second rotary body by utilizing the control torque transmitted from the torque producing unit to the planetary gear mechanism and has a space at an interface where the first rotary body is brought into sliding contact with the planetary gear.