A liquid ejecting head unit includes: a plurality of liquid ejecting heads, each of which has a nozzle array in which nozzles ejecting liquid droplets are arrayed; a base plate to which the plurality of liquid ejecting heads are fixed in a state being positioned at predetermined positions thereof; and positioning pins which are fixed to the base plate and engaged with positioning holes formed in the liquid ejecting heads. Each of the positioning pins is held in a holding hole provided in a fixing plate fixed to the base plate. A reference plate is joined to a surface of each of the fixing plates. Further, in each of the reference plates, there are provided: an insertion hole in which the positioning pin is substantially inscribed; and a minute hole that serves as a reference for positioning the positioning pin to the base plate.