Abstract: An electronic device comprising a solar cell, a secondary battery charged by an output from the solar cell, an illumination detector for detecting the brightness of the environment of the solar cell based on the output from the solar cell, a display unit, an electroluminescence (EL) element for illumining the display unit, an attitude detector for detecting an attitude of the electronic device, a driver for driving the EL element on the basis of the attitude of the electronic device detected by the attitude detector and the result of the detection by the illumination detector. Only when the illumination detector detects that the environment of the solar cell is dark, and the attitude detector detects that the electronic device takes a specified attitude, the EL element is turned on. Otherwise, the illuminator is not turned on. Thus, wasteful power consumption is suppressed to prolong the solar cell's service life.