A multilink-type internal combustion engine includes a power transmission structure capable of transmitting rotation of a crankshaft to a pivot shaft. The power transmission structure comprises: a planet gear mechanism having a sun gear mounted on the crankshaft; a drive gear provided on a ring gear section of the planet gear mechanism; a driven gear mounted on the pivot shaft and meshing with the drive gear; and an adjustment mechanism for switching a rotation direction of a carrier of the planet gear mechanism to thereby adjust a meshing phase of the driven gear relative to the drive gear.