A valve timing controller includes a first rotating element and a second rotating element. The controller further includes a link mechanism part including arm members for coupling the first and second rotating elements. The controller also includes a gear part including a first gear and a second gear to convert outside rotating torque to control torque for motion of the arm members due to coupling of and relative motion of the first and second gears. Additionally, the controller includes a separation member disposed between the gear part and the link mechanism part for separating a thrust gap of the gear part and a thrust gap of the link mechanism part.