A foldable electronic device is provided. The foldable electronic device includes a foldable housing that can be fold/unfolded with respect to a folding shaft, a display that is visible through one surface of the foldable housing, a photosensor which is arranged inside the foldable housing and which includes a light-receiving unit for measuring the intensity of light emitted at the electronic device, and at least one processor operationally connected to the photosensor and the display, wherein the at least one processor is configured to acquire an illuminance value by using the photosensor, acquire data related to the incident angle of the light, emitted on the electronic device, by using the photosensor, correct the illuminance value based on the data related to the incident angle of the light, determine the brightness of a first part of the display based on the corrected illuminance value, and determine the brightness of a second part of the display based on the illuminance value and the angle formed by the foldable housing.