PURPOSE: To enable to eliminate the extension of bonding material in grooves at the assembling time and to print in high density by forming grooves for accumulating ink on a plate material and a heater at the tops of projecting strips of a base plate, and bonding the base plate to the plate material with the bonding surface except the engaging surface of the grooves and the projections.

CONSTITUTION: A base plate 9 which has projecting strips 8 in projecting height lower than the depth of grooves 2 and in width substantially equal to the grooves 2 is provided. A heater 4 is formed on the tops of the nozzles 7 side of the strips 8, and electrodes 11, 12 which make contact with both electrodes of the heater 4 are formed in one row on the top surfaces of the strips 8. Accordingly, the pitch of the heater 4 can be reduced, thereby printing in high density. Particularly in assembling, the position of the heater 4 can be determined merely by engaging the strips 8 with the grooves 2, an adhesive 14 is not extended into the grooves 8, the assembling can be facilitated, and the sectional area of the groove 2 and the area of the hole of the nozzle 7 can be equalized to form uniform dots.