To provide a microlens forming method capable of simply performing the alignment of the optical axis of an optical device (an optical element, an optical part or the like) with that of a microlens at a low cost.

A photomask (1) having a microlens pattern for forming the microlens and an alignment mark pattern is used, and the alignment mark (5) of the microlens is aligned with the alignment mark (4) of the optical element by setting the alignment mark of the optical device having the optical element (3) to the light emitting or receiving center of the optical element to align the optical axis of the microlens with that of the optical device. A film (9) for a lens marker, to which the microlens pattern having an alignment mark (8) at the center thereof is transferred, is formed on a substrate (12), and a liquid resin for the microlens is injected on the film for the lens marker to form a liquid microlens which is, in turn, irradiated with UV rays to be cured to form the microlens.