Vectors for transforming plants with the use of agrobacteria which have been modified so as to elevate the possibility of the recognition of the border sequences of the vectors by vir proteins of the agrobacteria, thereby lowering the possibility of the transfer of DNAs other than T-DNA into plant chromosomes. More particularly, the above-vectors are those to be used in transforming plants which have right and left border sequences which can be recognized by the vir proteins of the agrobacteria, a T-DNA sequence which is located between these border sequences and into which a gene to be transferred into plants can be inserted, and a replication origin enabling the replication of the vectors in bacteria, characterized by having a plural number of left border sequences.