In a liquid-cooling system for a notebook personal computer having a body part including a CPU and a chip set respectively mounted on a mother board and an HDD, and a display part rotatably supported by the body part, a heat receiving head is fixed to at least one heat generation part including the CPU. A tube filled with cooling liquid is connected to the heat receiving head. The tube connected to the heat receiving head is disposed in series on at least one heat generation part including the chip set so as to collect the heat generated from each heat generation part. The tube is also laid in a meandering or zigzagging pattern between a liquid crystal panel and a housing of the display part. The heat generated from each heat generation part is absorbed at part of the tube by the cooling liquid that circulates in the tube and functions as a heat transfer medium. The absorbed heat is then radiated at another part of the tube. Consequently, the heat generated from the chip set including the CPU and other heat sources such as the HDD can be radiated together to the outside.