A valve timing adjusting device includes a first rotor rotating integrally with a crankshaft; a second rotor secured integrally with an intake or exhaust camshaft; a first hole formed passing through radially to a shoe formed inside the first rotor; a second hole formed through the shoe, intersecting the first hole; a coil spring pressing a lock pin received in the first hole to thereby engage the lock pin into a concavity formed on the outer peripheral surface of the second rotor; and a shaft inserted into the second hole in order to prevent the coil spring from dashing out.