Abstract: An external light source providing device comprises a main body, a power supply module, a light-emitting module and a cover. A first and second accommodating spaces are formed on the main body. A mobile electronic device is coupled in the first accommodating space. The power supply module and the light-emitting module are disposed in the second accommodating space. The light-emitting module and the power supply module are electrically connected to each other so that the light-emitting module can be powered by the power supply module to emit light towards the first accommodating space to provide the brightness required by the mobile electronic device. The cover is disposed on the second accommodating space so that the power supply module and the light-emitting module are covered. At least one hole is disposed on the cover so that the light of the light-emitting module can be projected through it.