The present invention provides an analysis method by which a DNA element can be identified with higher sensitivity, and a transcription amount of the DNA element can be determined. The present invention is a method for decoding a base sequence of a nucleic acid corresponding to an end region of RNA, including: a preparing-decoding step of preparing, using a template RNA, at least one nucleic acid selected from the group consisting of: an RNA nucleic acid of a 5′-end region of the template RNA or a complementary DNA nucleic acid corresponding to the 5′-end region of the template RNA; an RNA nucleic acid of 3′-end region of the template RNA or a complementary DNA nucleic acid corresponding to the 3′-end region of the template RNA; an RNA nucleic acid of a partial region of an antisense strand or a sense strand for a full length of the template RNA; and combinations thereof or a nucleic acid having a sequence that has two or more linked sequences thereof, wherein the template RNA to be used in the preparing-decoding step is a nascent RNA. The DNA element can be identified and analyzed with higher accuracy and higher sensitivity by determining information on the decoded sequence of the nucleic acid and mapping the DNA element to the genome.