(Problem)To provide technology for easily manufacturing a light illuminating apparatus suitable for the performance of a power device(Problem-solving means)A light emitting device (M) includes a substrate (410) having an anode pattern (310) and a cathode pattern (320), and at least one light emitting element (330) connected to the anode pattern and the cathode pattern. The substrate has a connecting part (350) at each of two ends of the anode pattern extending in a connection direction with other light emitting device that is different from the light emitting device (M) to connect the light emitting device (M) to other light emitting device, and a connecting part (350) at each of two ends of the cathode pattern extending in the connection direction to connect the light emitting device (M) to other light emitting device.