A lamp according to one or more embodiments includes a tube which forms a light-emitting space, an electrode main body which is disposed in the tube, and an emitter surface metal layer which includes an alkali metal oxide and/or an alkaline earth metal oxide, and covers the electrode main body. The emitter surface metal layer may include cesium (Cs) and may further include at least one selected from the group consisting of beryllium oxide (BeO), magnesium oxide (MgO), calcium oxide (CaO), strontium oxide (SrO), barium oxide (BaO), cesium oxide (CsO) and radium oxide (RaO). Therefore, discharge may be easily activated because of a high secondary electron emission coefficient. Thus, a light-emitting efficiency may be enhanced and dark start characteristics may be improved.