An integrated circuit mounted board includes a printed wiring board and an integrated circuit bare chip mounted on the printed wiring board. The printed wiring board includes a metal base, an insulating member made of an insulating material and disposed on the metal base, and a wiring pattern disposed on the insulating member. The wiring pattern includes an electrode part to which the integrated circuit bare chip is electrically coupled. The insulating member includes an under region being opposite to the electrode part. The metal base includes a metal substrate and a metal portion protruding from the metal substrate. The metal portion is buried in the under region of the insulating member.