Assist probe and method of using the same

Detection method of a target gene can be improved and polygenic simultaneous detection of sensitivity in the PALSAR method, the assist probes used in the method, as well as a method of forming a signal probe polymer using the assist probe. 5 'nucleic acid region from the end portion in order X, the first probe nucleic acid region Y and a nucleic acid region Z is provided, and 5' nucleic acid region from the end portion in order X ', a nucleic acid region Y' and a nucleic acid region Z 'are provided the second probe, and using an assist probe having a hybridizable target area into a plurality of the same nucleic acid region and target gene and the first probe, to form a signal probe polymer, a method of detecting a target gene, the assist probe, 5 'said nucleic acid region X from the end in order, Y, X and structure the target area is provided, or 5' from said end in order target region and the nucleic acid regions Z, Y, Z is provided and to have obtained structure.