To provide a lens array holder which can position a light emitting face, a lens array and a light receiving face, can correct a deflection of the lens array and can obtain high-quality images without requiring special parts, adjustment, measurement and the like, a lens array unit, a printing head, a positioning device and a manufacturing method for a lens array unit.

The lens array unit 1 includes the lens array 2, and the lens array holder 3 for holding the lens array 2 and a pair of positioning pins 4 with a first and a second reference faces 4a and 4b at both end faces. The first reference face 4a is butted against a reference face at the light emitting face side and the second reference face 4b is butted against a reference face at the light receiving face side, whereby a relative position of the light emitting face, the lens array 2 and the light receiving face is determined.