Nucleobase sequence determination method

A sequencing methods of nucleic acid, having respectively at least two primers having a tag sequence, the presence of specific primers and DNA polymerase to a template nucleic acid, the step of amplifying the template nucleic acid, the wherein the tag sequence primer 'having a tag sequence on the terminal side, 3' 5 primers distally having 3 nucleotides or more particular nucleotide sequence; and the amplified fragment obtained in the above step to include the step of direct sequencing nucleobase sequence determination method according to claim.