A lamp system comprising: an array-type light-emitting device comprising a power supply terminal, a ground terminal and a plurality of pixel circuits (PIX1-PIXn) electrically coupled in parallel, and spatially arranged in a matrix, wherein each pixel circuit (PIXj, with 1 ≤ j ≤ n) includes a light-emitting element (213_j) and a current source (214_j) coupled in series between the power supply terminal and the ground terminal; and a power supply circuit having output terminals (AP/AN) coupled to the power supply terminal and the ground terminal of the array-type light-emitting device via a power supply cable and structured to supply electric power to the array-type light-emitting device, wherein the power supply circuit comprises: a DC/DC converter having an output coupled to the array-type light-emitting device via the power supply cable; and a power supply control circuit structured to set a target value, and to control the DC/DC converter such that a control target voltage approaches the target value, wherein the control target voltage is a voltage that occurs at one of the output terminal of the DC/DC converter and the power supply terminal of the array-type light-emitting device; characterised in that the target value is set according to a light distribution pattern of the array-type light-emitting device. an array-type light-emitting device comprising a power supply terminal, a ground terminal and a plurality of pixel circuits (PIX1-PIXn) electrically coupled in parallel, and spatially arranged in a matrix, wherein each pixel circuit (PIXj, with 1 ≤ j ≤ n) includes a light-emitting element (213_j) and a current source (214_j) coupled in series between the power supply terminal and the ground terminal; and a power supply circuit having output terminals (AP/AN) coupled to the power supply terminal and the ground terminal of the array-type light-emitting device via a power supply cable and structured to supply electric power to the array-type light-emitting device, wherein the power supply circuit comprises: a DC/DC converter having an output coupled to the array-type light-emitting device via the power supply cable; and a power supply control circuit structured to set a target value, and to control the DC/DC converter such that a control target voltage approaches the target value, wherein the control target voltage is a voltage that occurs at one of the output terminal of the DC/DC converter and the power supply terminal of the array-type light-emitting device; characterised in that the target value is set according to a light distribution pattern of the array-type light-emitting device. a DC/DC converter having an output coupled to the array-type light-emitting device via the power supply cable; and a power supply control circuit structured to set a target value, and to control the DC/DC converter such that a control target voltage approaches the target value, wherein the control target voltage is a voltage that occurs at one of the output terminal of the DC/DC converter and the power supply terminal of the array-type light-emitting device; characterised in that the target value is set according to a light distribution pattern of the array-type light-emitting device.