An electronic device is disclosed. The wearable electronic device, according to various embodiments, comprises: a battery; an illuminance sensor capable of measuring the brightness of the outside of the wearable electronic device; a transparent member capable of transmitting light incident from the outside; a light adjusting member arranged on at least one portion of the transparent member and capable of adjusting the transmittance of the incident light; a projector capable of outputting an image through the transparent member; and a processor, wherein the processor may be configured so as to measure the remaining capacity of the battery and the brightness of the outside, and when the remaining capacity is within a first predetermined range, adjust the transmittance to a first predetermined transmittance and adjust the output luminance of the projector to a first predetermined luminance on the basis of the brightness, and when the remaining capacity is within a second predetermined range, adjust the transmittance to a second predetermined transmittance and adjust the output luminance of the projector to a second predetermined luminance which is lower than the first predetermined luminance on the basis of the brightness. In addition, various embodiments may be provided.