Plurality of glass droplets are simultaneously dropped toward center of a regular polygon of each unit on a first transfer surface of a first forming die where a plurality of the units is regularly arranged along the same plane, taking, as one unit, three or more first optical transfer surfaces for forming a lens portion placed in such a manner as to overlap vertices of the regular polygon respectively. After the divided glass droplets flow on the first transfer surface, are connected to each other between adjacent units, and are formed into united glass, and before the united glass hardens completely, a second forming die including a plurality of second optical transfer surfaces corresponding respectively to the plurality of first optical transfer surfaces is pressed relatively against the united glass on the first forming die to form the united glass, and released from the dies.