A device unit for a throttle body, in which sealing ability between a device block and a device cover by resin-welding is enhanced. The device unit has the device block (50) detachably or undetachably installed on the throttle body (2) in which a throttle valve (14) for opening and closing a bore (7) is installed and having at least one modularized device part, and also has the device cover (60) for covering the device part of the device block (50). A ridge (194) facing the entire periphery of an outer peripheral part (206) of the device cover (60) is formed on the device block (50). The device cover (60) is resin-welded to the device block (50), with the forward end of the ridge (194) used as the portion to be welded to the device block. The device block (50) having the ridge (194) is formed of an absorptive resin material with high laser beam absorptance. The device cover (60) is formed of a light transmissive resin material with high laser beam transmittance. The device cover (60) is resin-welded to the device block (50) by a laser beam.
