A light emitting device comprising: a light emitting diode chip; a heat conductive plate which is made of a heat conductive material and said light emitting diode chip is mounted thereon; a sub-mount member of a planar plate which is dimensioned to be larger than said light emitting diode chip and smaller than said heat conductive plate, said sub-mount member being disposed between said light emitting diode chip and said heat conductive plate and being configured to relieve a stress acting upon said light emitting diode chip due to a difference in linear thermal expansion coefficient between said light emitting diode chip and said heat conductive plate; a dielectric substrate stacked on said heat conductive plate, said dielectric substrate being provided on a surface opposite of said heat conductive plate with a pair of lead patterns for electrical connection respectively with electrodes of said light emitting diode chip, said dielectric substrate being formed with a through-hole through which said sub-mount member is exposed; an encapsulation member being made of a transparent and elastic material and configured to encapsulate said light emitting diode chip; a lens superimposed on said encapsulation member; and wherein said sub-mount member includes a reflection film disposed around a juncture of said light emitting diode chip and is configured to reflect a light emitted from a side face of said light emitting diode chip; characterized in that said sub-mount member is selected to have a thickness such that said reflection film has its surface spaced from said heat conductive plate by a greater distance than said dielectric substrate, and is configured to prevent absorption of said light radiated from said side face of said light emitting diode chip in a surface or a side wall of said dielectric substrate, and a color conversion member is deposited on a surface of said dielectric substrate to convert a color of said light radiated from said light emitting diode chip or said reflection film. a light emitting diode chip; a heat conductive plate which is made of a heat conductive material and said light emitting diode chip is mounted thereon; a sub-mount member of a planar plate which is dimensioned to be larger than said light emitting diode chip and smaller than said heat conductive plate, said sub-mount member being disposed between said light emitting diode chip and said heat conductive plate and being configured to relieve a stress acting upon said light emitting diode chip due to a difference in linear thermal expansion coefficient between said light emitting diode chip and said heat conductive plate; a dielectric substrate stacked on said heat conductive plate, said dielectric substrate being provided on a surface opposite of said heat conductive plate with a pair of lead patterns for electrical connection respectively with electrodes of said light emitting diode chip, said dielectric substrate being formed with a through-hole through which said sub-mount member is exposed; an encapsulation member being made of a transparent and elastic material and configured to encapsulate said light emitting diode chip; a lens superimposed on said encapsulation member; and wherein said sub-mount member includes a reflection film disposed around a juncture of said light emitting diode chip and is configured to reflect a light emitted from a side face of said light emitting diode chip; characterized in that said sub-mount member is selected to have a thickness such that said reflection film has its surface spaced from said heat conductive plate by a greater distance than said dielectric substrate, and is configured to prevent absorption of said light radiated from said side face of said light emitting diode chip in a surface or a side wall of said dielectric substrate, and a color conversion member is deposited on a surface of said dielectric substrate to convert a color of said light radiated from said light emitting diode chip or said reflection film.