A white light source device includes a first light-emitting element, and at least one second light-emitting element. The first light-emitting element includes a first light-emitting unit and a first wavelength conversion unit, and emits a first light beam. Each of the second light-emitting elements includes a second light-emitting unit and a second wavelength conversion unit, and emits a second light beam. An emission spectrum of the second light beam is different from an emission spectrum of the first light beam. The first light beam and the second light beam are mixed into a white light beam, and a color fidelity index of the white light beam is greater than 90.