Laser irradiation apparatus and laser processing apparatus

A laser irradiation apparatus comprising:

• a laser array configured with a plurality of laser elements including a first laser element and a second laser element;
• and
• a cooling substrate configured to cool the laser array, wherein
• the cooling substrate includes:
• a substrate including a mounting surface on which the laser array is mounted;
• a supply flow path extending in a direction crossing the mounting surface and configured to supply a coolant to an inside of the substrate;
• a first flow path extending along the mounting surface and configured to cool the first laser element via the substrate;
• and
• a second flow path extending along the mounting surface and configured to cool the second laser element via the substrate,
• in a plan view of the mounting surface, each of the first flow path and the second flow path is branched from the supply flow path between the first laser element and the second laser element, and
• the coolant flows to the first flow path and the second flow path via the supply flow path.