A resin composition for production of an optical element being adapted to form the optical element has a characteristics of which, when W1 / 2 (° C.) represents, regarding a crest portion in a loss factor / temperature curve obtained by measuring the loss factor of the resin composition relative to a change in the temperature, the width of the crest portion at the position of ½ of the maximum value of the loss factor in the crest portion temperature range; W0.1 (° C.) represents, regarding the crest portion, the width of the crest portion at the position of 0.1 of the maximum value of the loss factor; and DeltaW (° C.), the difference between the widths of the two crest portions, is set to be DeltaW=W0.1-W1 / 2, the DeltaW is in the range of from 16° C. to 31° C.