DNA having promoter activity for expressing an exogenous gene specifically in vegetative growth tissue (particularly, stems and/or leaves) is provided. The DNA is a rice OsGA3ox2 gene promoter which has a sequence indicated by SEQ ID NO. 1, or a portion of said sequence whose promoter activity is equivalent to that of said sequence indicated by SEQ ID No. 1. An expression vector containing an exogenous gene expressibly linked to the promoter is also provided. A plant cell transformed with the expression vector, a plant regenerated from the plant cell, a progeny of the plant, a propagator of the plant, and a seed obtained from the progeny are also provided. A method for introducing an exogenous gene into plants using an expression vector is also provided.