Abstract: The present invention relates to a portable computer having a power supply in the form of a battery pack, the battery pack being both electrically and physically separable from the portable computer. The portable computer has a power management system capable of decreasing power consumption by differentially supplying power according to power management mode, including a base having internally a storage member and provided with at least one opening at one side of the base, a battery pack coupled to the base to supply a power and having at least one lug inserted into the at least one opening, at least one lever coupled to the base and combined or separated with the at least one lug, a switch provided in the base, wherein the switch generates a signal of operating the power management system when the at least one lever is separated from the at least one lug.