An ink jet apparatus includes an ink jet recording head having a housing, an ink container in the housing for containing ink, ejection outlets for ejecting the ink supplied from the ink container, and energy generating elements for generating energy contributable to the ejection of the ink through the ejection outlets, the housing being provided with a cavity. The ink jet recording head further comprises electric contacts for supplying the energy, the contacts being provided on a wall defining the cavity and a carriage on which the ink jet recording head is mounted, the carriage being provided with a contact member having electric contacts for electric coupling with the aforementioned contacts. The ink jet recording head is mounted on the carriage with the contact member being in the cavity. The housing is provided with a window extending from a cavity to permit observation of the contact member.