Provided are methods of isolating and amplifying nucleic acids from and in a nucleic acid-containing sample. The nucleic acid isolation method includes contacting a nucleic acid-containing sample to a silanized solid support to capture nucleic acids to the silanized solid support and treating the nucleic acid-captured solid support with an alkaline solution of pH 9 to 14. The nucleic acid amplification method includes contacting a nucleic acid-containing sample to a silanized solid support to capture nucleic acids to the silanized solid support; treating the nucleic acid-captured solid support with an alkaline solution of pH 9 to 14; and adding a nucleic acid amplification solution to the resultant solution after the alkaline solution treatment to perform nucleic acid amplification.