An integrated quantum cascade laser includes: a laser structure including first to third regions arranged in a direction of a first axis, the laser structure including a substrate and a laminate including a core layer; first and second metal layers disposed on the third region; third and fourth metal layers disposed on the first region; first to fourth bump electrodes disposed on the first to fourth metal layers, respectively; first and second semiconductor mesas provided in the first region, each of the first and second semiconductor mesas including the core layer; and a distributed Bragg reflector provided in the second region, the distributed Bragg reflector having one or more semiconductor walls. The first and second metal layers are electrically connected to the first and second semiconductor mesas, respectively. The third and fourth metal layers are isolated from the first and second metal layers.