An ink tank provided with a supply port for supplying the ink contained therein and an electric contact for information transmission is smoothly and securely attached to an attachment section of a printing apparatus while achieving secure connection of an electric contact section at the same time. The ink tank is configured to be attachable to the attachment section by positioning a first engagement section at a first fitting section on the attachment section, and then by rotating the ink tank around the positioned first engagement section to lock a second engagement section to a second fitting section on the attachment section. The supply port and a positioning section for the contact are disposed on the bottom face of the ink tank so as to be on the respective two sides of the center line in the width direction of the ink tank therebetween.