A light emitting device (100, 100', 100", 100a), comprising: a carrier; a light emitting element, disposed on the carrier and electrically connected to the carrier; a transparent plate, wherein the transparent plate is disposed on the carrier and is having at least one through hole formed therein, the transparent plate comprising: a flat-portion, having an upper surface and a lower surface opposite to the upper surface, and the lower surface directly disposed on the carrier; and a lens-portion, covering the light emitting element, and having a light incident surface, a light emitting surface opposite to the light incident surface, and a first side surface and a second side surface connecting the upper surface and the light emitting surface, wherein the light emitting element is suitable for emitting a light beam, a first partial beam of the light beam passes through the light incident surface and leaves from the light emitting surface, a second partial beam of the light beam passes through the light incident surface and is transmitted to the first side surface or the second side surface, and the first side surface or the second side surface reflects at least a part of the second partial beam of the light beam to be passed through the light emitting surface; a permeable membrane structure disposed on a surface of the transparent plate, the permeable membrane structure covering an end of the through hole far away from the light emitting surface; and wherein the first side surface and the second side surface are planes and a slope of the first side surface and a slope of the second side surface are different, or in that the first side surface and the second side surface are respectively a plane and a curved surface. a carrier; a light emitting element, disposed on the carrier and electrically connected to the carrier; a transparent plate, wherein the transparent plate is disposed on the carrier and is having at least one through hole formed therein, the transparent plate comprising: a flat-portion, having an upper surface and a lower surface opposite to the upper surface, and the lower surface directly disposed on the carrier; and a lens-portion, covering the light emitting element, and having a light incident surface, a light emitting surface opposite to the light incident surface, and a first side surface and a second side surface connecting the upper surface and the light emitting surface, wherein the light emitting element is suitable for emitting a light beam, a first partial beam of the light beam passes through the light incident surface and leaves from the light emitting surface, a second partial beam of the light beam passes through the light incident surface and is transmitted to the first side surface or the second side surface, and the first side surface or the second side surface reflects at least a part of the second partial beam of the light beam to be passed through the light emitting surface; a flat-portion, having an upper surface and a lower surface opposite to the upper surface, and the lower surface directly disposed on the carrier; and a lens-portion, covering the light emitting element, and having a light incident surface, a light emitting surface opposite to the light incident surface, and a first side surface and a second side surface connecting the upper surface and the light emitting surface, wherein the light emitting element is suitable for emitting a light beam, a first partial beam of the light beam passes through the light incident surface and leaves from the light emitting surface, a second partial beam of the light beam passes through the light incident surface and is transmitted to the first side surface or the second side surface, and the first side surface or the second side surface reflects at least a part of the second partial beam of the light beam to be passed through the light emitting surface; a permeable membrane structure disposed on a surface of the transparent plate, the permeable membrane structure covering an end of the through hole far away from the light emitting surface; and wherein the first side surface and the second side surface are planes and a slope of the first side surface and a slope of the second side surface are different, or in that the first side surface and the second side surface are respectively a plane and a curved surface.