A liquid-ejection head unit includes a head, an electric-circuit board, electronic components, and a storage tank. The head includes a frame member and ejects droplets of liquid. The electronic components are mounted on the electric-circuit board and connected to the head. The storage tank stores liquid supplied to the head. The electric-circuit board is disposed between the frame member of the head and the storage tank to form a single multi-layered structure. The electronic components of the electric-circuit board are accommodated in at least one of a first internal space defined by the frame member of the head and the electric-circuit board and a second internal space defined by the electric-circuit board and the storage tank.