A light source unit of a semiconductor-type light source of a vehicle lighting device, comprising: a mount member; a plurality of light emitting chips (40 to 44) of semiconductor-type light sources that are intensively mounted on the mount member, for radiating light from a front face and a side face other than a surface on which the light emitting chips (40 to 44) are mounted on the mount member; a control element that is mounted on the mount member, for controlling light emission of the light emitting chips (40 to 44); a wiring element (51 to 57, 61 to 65, 610 to 650) that is mounted on the mount member, for feeding power to the light emitting chips (40 to 44) via the control element; a bank member that is mounted on the mount member, for surrounding all of the plurality of the light emitting chips (40 to 44) and a part of a wiring element (51 to 57, 61 to 65, 610 to 650); and an optically transmissible sealing member that is injected into the bank member, for sealing all of the plurality of the light emitting chips (40 to 44) and a part of the wiring element (51 to 57, 61 to 65, 610 to 650), characterized in that a range of an inner circumferential face of the bank member that surrounds the sealing member is a range in which a start point at which at least a surface of the sealing member warps upward with respect to an inner circumferential surface of the bank member by means of a surface tension is coincident with or is substantially coincident with a critical point at which light that is radiated from a given point that is the shortest from the inner circumferential face of the bank member among the light emitting chips (40 to 44) is fully reflected on an interface between the sealing member and a pneumatic air layer. a mount member; a plurality of light emitting chips (40 to 44) of semiconductor-type light sources that are intensively mounted on the mount member, for radiating light from a front face and a side face other than a surface on which the light emitting chips (40 to 44) are mounted on the mount member; a control element that is mounted on the mount member, for controlling light emission of the light emitting chips (40 to 44); a wiring element (51 to 57, 61 to 65, 610 to 650) that is mounted on the mount member, for feeding power to the light emitting chips (40 to 44) via the control element; a bank member that is mounted on the mount member, for surrounding all of the plurality of the light emitting chips (40 to 44) and a part of a wiring element (51 to 57, 61 to 65, 610 to 650); and an optically transmissible sealing member that is injected into the bank member, for sealing all of the plurality of the light emitting chips (40 to 44) and a part of the wiring element (51 to 57, 61 to 65, 610 to 650), characterized in that a range of an inner circumferential face of the bank member that surrounds the sealing member is a range in which a start point at which at least a surface of the sealing member warps upward with respect to an inner circumferential surface of the bank member by means of a surface tension is coincident with or is substantially coincident with a critical point at which light that is radiated from a given point that is the shortest from the inner circumferential face of the bank member among the light emitting chips (40 to 44) is fully reflected on an interface between the sealing member and a pneumatic air layer.