Disclosed is a power supply device using a supercapacitor for engine start-up. A power supply device using a supercapacitor for engine start-up according to the present invention converts a switch connected to a supercapacitor module to an ON state by detecting the start time of an engine start-up, thereby allowing electric energy stored in the supercapacitor module to be used to rotate an engine starter motor. Accordingly, installing the power supply device for engine start-up is made easy, thus saving time and cost. Moreover, a start-up method is changed when the state of an engine changes according to the environment, thus enabling a smoother start-up. Furthermore, the capacity of the supercapacitor used can be reduced. Therefore, a power supply device that uses a cheaper supercapacitor module for engine start-up can be provided.