A control device of an internal combustion engine includes: a variable valve device including: first and second rocker arms; a cam; a rocker shaft provided with a lubricating oil passage; a pin switching the first and second rocker arms between a coupling state and a non-coupling state; a biasing member biasing the pin; a switching oil passage capable of supplying oil pressure to the pin in a direction opposite to a biasing direction; a lash adjuster; and a supplying oil passage, capable of supplying oil pressure to the pin in the biasing direction of the biasing member and supplying oil pressure into the lash adjuster, a hydraulic pump; an oil pressure control valve; and a control unit controlling the oil pressure control valve to always supply the supplying oil passage with oil pressure higher than oil pressure within the lubricating oil passage, during driving of an internal combustion engine.