According to an embodiment of the present disclosure, a portable lighting device capable of adaptive brightness control includes: a light irradiation unit that irradiates light; a brightness sensing unit that measures the brightness of a region in front of a current position at a predetermined distance; and a control unit that controls the amount of light to be irradiated by the light irradiation unit depending on the brightness measured by the brightness sensing unit. Herein, the control unit controls the amount of light by changing the width of an ON pulse period in which the light irradiation unit is operated within a discrete signal controlling the light irradiation unit or by changing the intensity of light in response to a continuous signal controlling the light irradiation unit.