An ink jet head which enables using plural types of ink in the head to accommodate varying types of paper or objects to be imprinted. The single ink jet head includes plural cartridges which are selected in accordance with the property of the medium which is imprinted or the ink finish which is desired. The ink jet head includes a discharge element which is excitable under a controller to comply with the characteristics of the type of ink sensed by detecting the electrical conductivity of the ink.