A self-luminescent light source for a liquid crystal display watch characterized by comprising a fluorescent substance layer which has a light reflectivity and which contains radioactive element promethium (.sup.147 Pm) in at least a part thereof, a reflective layer which is disposed on one surface of the fluorescent substance layer and which serves to reflect and scatter fluorescence from the fluorescent substance layer, a case which is disposed on the side of the reflective layer remote from the fluorescent substance layer and which serves to perform shielding from Bremsstrahlung ascribable to beta rays given out from the promethium, a first cover which is disposed on the side of the fluorescent substance layer remote from the reflective layer and which serves to absorb the beta rays given out from the promethium and to transmit the light from the fluorescent substance layer, and a second cover which is disposed on the side of the first cover remote from the fluorescent substance layer and which serves to perform shielding from Bremsstrahlung ascribable to the beta rays given out from the promethium and to transmit the light from the fluorescent substance layer.