1. An image sensing apparatus characterized by comprising: a control device which acquires a first control value on the basis of a light emission amount of an illumination device which illuminates an object and an illuminance of the object before illuminated by the illumination device, acquires a second control value by applying the first control value to a predetermined function, and adjusts white balance of an image signal to be output from an image sensing device on the basis of the first and second control values.