An infrared data communication module (A1) includes a substrate (1) consisting of a first layer (1A) and a second layer (1B), where the first layer is formed with a recess (11) open at its obverse surface, and includes the opening of the recess (11) and the second layer is fixed to the first layer (1A) on the side opposite from the opening. The module also includes a bonding conductor layer (6A) covering at least the bottom surface of the recess (11), a light emitting element (2) mounted on the bonding conductor layer (6A), and a heat dissipating conductor layer (6C) sandwiched between the first layer (1A) and the second layer (1B) and connected to the bonding conductor layer (6A).