To miniaturize and make compact a fluid injector, to reduce cost, to increase space saving and especially to efficiently clean a large vehicle such as a large truck or the like.

A fluid injector is provided with a main pipe part 2, into which high pressure fluids W are fed, a plurality of branch-pipe parts 3,..., branched from a plurality of positions in the main pipe part 2, having injection nozzles 3e,..., in the tip thereof for injecting the fluids W and formed to be partially flexible, a tip regulating part 4 having regulation holes 5,..., through which the tips of the branch-pipe parts 3,..., are inserted with specified play S,..., and a driving mechanism part 6 for displacing the tip regulating part 4 and the main pipe part 2 relative to each other.