PURPOSE: To produce an inexpensive ink jet head in high yield with high reliability by dissolving the solid layer provided on a substrate according to the pattern of liquid passages by a high concn. solution and washing the interior of the head with dissolving solutions successively lowered in concn.

CONSTITUTION: In the production of an ink jet head, at first, liquid emitting energy generating elements are arranged to the upper surface of a substrate 1 functioning as a part of a passage constituting member and solid layers 4 are laminated to the predetermined regions of the upper surfaces of said elements. Next, an active energy ray curable material layer 7 is laminated to the substrate so as to cover the solid layers 3 and a second substrate 4 having an active energy beam blocking layer 8 preliminarily laminated to the surface thereof is laminated to said material layer 7. Continuously, the whole is irradiated with active energy beam and the material 7 is cured to form a cured resin layer and, at the same time, both substrates 1, 2 are mutually bonded. After the solid layers 3 are dissolved by a high conc. dissolving solution, the interior of the head is washed with dissolving solutions successively reduced in concn.