A driving device includes a dimmer, a rectifying-filtering unit, a rectifying-dividing unit, a control unit, and a voltage transforming unit. The dimmer is used for receiving an alternating current (AC) voltage from a power supply, and generating a primary voltage for controlling the brightness of a luminous element. The rectifying-filtering unit is used for rectifying and filtering the primary voltage to generate a secondary voltage. The rectifying-dividing unit is used for rectifying and dividing the primary voltage to generate a detecting voltage. The control unit is used for receiving the secondary voltage, and generating a pulse voltage whose duty cycle is variable with the detecting voltage. The voltage transforming unit is used for transforming the secondary voltage to a driving voltage for driving the luminous element to emit light according to the pulse voltage. A related electronic apparatus is also provided.