DNA material contributing to an increase in a target protein in a plant seed was newly discovered, and so a use thereof is disclosed. To said end, in the present disclosure, DNA set forth in one of the belowmentioned (a) to (d) that promotes the expression of a target protein in plant seeds is introduced into a plant: (a) DNA having the base sequence represented by sequence number 1, 2, 3, or 4； (b) DNA that hybridizes under stringent conditions with DNA comprising a complementary base sequence to the base sequence represented by sequence number 1, 2, 3, or 4； (c) DNA having a base sequence that is at least 90% identical to the base sequence represented by sequence number 1, 2, 3, or 4； and (d) DNA comprising a base sequence represented by SEQ ID No. 1, 2, 3 or 4, wherein at least one base has been substituted, deleted, inserted, or added.
