To obtain a cloning vector suitable for a cycle sequence method and a transcription sequence method.

In this vector which is transduced into a host cell and is proliferated with proliferation of the host cell, the vector is provided with a foreign DNA fragment introduction domain which contains a first promoter site and a second promoter site each containing a transcription starting point according to an RNA polymerase and a restriction enzyme recognition site for introducing a foreign DNA fragment into a domain laid between the first promoter site and the second promoter site. The foreign DNA fragment introduction domain is provided with a predetermined analysis unnecessary sequence having 50 base pairs or more between the transcription starting points of the first promoter site and the second promoter site from the restriction enzyme recognition site.