The present invention provides a flowering inducer comprising any one of the following proteins (A)-(C). (A) a protein comprising the amino acid sequence represented by SEQ ID NO:2 (B) a protein comprising an amino acid sequence having deletion, substitution and/or addition of one or several amino acids in the amino acid sequence represented by SEQ ID NO:2 and having a flowering-inducing activity and (C) a protein comprising an amino acid sequence having an identity of 60% or more with the amino acid sequence represented by SEQ ID NO:2 and having a flowering-inducing activity. This flowering inducer can be administered into a plant body from outside.