PURPOSE: To eliminate crosstalk and unify discharging performance, in the multi-array of a bubble jet type ink jet.

CONSTITUTION: A lid substrate 1 is constituted of a plurality of flow passages, communicating with a chamber for receiving recording liquid, and a recording liquid inflow port formed in the chamber. A substrate 2, having a bubble generating means, is engaged with the lid substrate 1 to constitute the chamber as well as the flow passages and is provided with a bubble generating means for generating bubbles 11 in recording liquid by a heat generating body 9. The bubble generating means produces bubbles 11 in the recording liquid by the conduction of an electric pulse and discharges the recording liquid as small drops 12 by a pressuer wave accompanied by the increase of volume of the bubbles 11. The lid substrate 1 is formed by the integral molding of plastic, whose acoustic impedance for transverse wave is 1.0×107N.S/m3 or less.