A light-emitting device with a long lifetime is provided. A light-emitting device with a low driving voltage is provided. In the light-emitting device, an electron-transport layer includes an organometallic complex of an alkali metal and an organic compound having an electron-transport property; the organometallic complex and the organic compound form an exciplex in combination; a value (eV) obtained by converting into energy a peak wavelength of an emission spectrum of the exciplex formed with the organometallic complex and the organic compound having a mass ratio of 1:1 is smaller than a difference (eV) between a HOMO level of the organometallic complex and a LUMO level of the organic compound by greater than or equal to 0.1 eV.