The printing head has connection terminals for performing an electrical connection of signals including drive signals of print elements by contacting connection terminals on an apparatus side when the head is mounted onto an ink jet printing apparatus. Connections of all terminals can be guaranteed by detecting contacts of a part of terminals. Among the terminals in the head, terminals whose distances from the connection terminals in the printing apparatus become maximum when a deviation occurred in the mounting are used as terminals for contact detection. For example, from among the connection terminals arranged in a planar area, which is rectangular-shaped, terminals positioned in corners are used as the terminals for the contact detection. When the contacts of these terminals are detected, the connections of all the terminals inside the area can be guaranteed.