To provide a method for manufacturing a liquid jet head in which discharge characteristics are stabilized by preventing occurrence of projecting etching residues on an etching face of a vibrating plate manufactured by etching, and a liquid jet device provided with the liquid jet head.

A pressure chamber of a flow passage forming substrate and the vibrating plate are formed by performing a first etching step, in which a high-concentration boron-doped layer is formed on one face of an Si substrate and etching is performed from the other face opposite to the one face to the halfway of the Si substrate with an etchant having a concentration adjusted to ≤30 wt.%, and then, a second etching step in which etching is performed from the part etched in the first etching step to a part reaching the high-concentration boron-doped layer with an etchant having a concentration lower than that of the etchant used in the first etching step.