A liquid ejecting head unit includes a base plate that holds a liquid ejecting head. A position determining pin is fitted into a position determining pin inserting hole in one of the liquid ejecting head and the base plate and is positioned on the other. A guide plate has a pin support hole inserted into the position determining pin. The guide plate is configured by a lowermost layer that is bonded to the other in which the position determining pin is positioned, a middle layer, and an uppermost layer. The pin support hole is configured by a first opening portion in the uppermost layer, a second opening portion in the lowermost layer, and a communication opening portion in the middle layer and allows the first and second opening portions to communicate with each other. The position determining pin is supported by the first and second opening portions.