Disclosed is a trace mRNA amplification method which can amplifies a shorter mRNA fragment at good efficiency in the same manner as for a longer mRNA fragment regardless of the length of the nucleotide sequence thereof. Also disclosed is use of the method. The trace mRNA amplification method comprises the following steps: a first step for preparing a mixed solution by adding dummy RNA to a solution containing trace mRNA; a second step for synthesizing antisense DNA by a reverse transcription reaction using the mixed solution as a template; a third step for synthesizing sense DNA complementary to the synthesized antisense DNA to form double-stranded DNA composed of the sense DNA and the antisense DNA; a forth step for ligating a promoter sequence for an RNA polymerase to the 5'-terminus of the sense DNA in the double-stranded DNA to prepare double-stranded DNA for amplification; and a fifth step for amplifying RNA from the double-stranded DNA for amplification by using the RNA polymerase.
