The present invention provides a digital camera which can adjust the start-up time in accordance with an amount of an electric energy of a power source being used at the time. The electric energy of the power source and the type thereof are determined on the basis of a voltage value of the power source which is inputted via a bus (steps 202, 206 and 218). If it is determined that the amount of the electric energy of the power source is large, the DC motor and the stepping motor are driven simultaneously so as to reduce the start-up time. If it is determined that the amount of the electric energy of the power source is small, the DC motor and the stepping motor are sequentially driven to save the electric energy.