The technology disclosed in the present specification relates to a simplified next-generation sequencing library preparation method using only two enzymes. Provided is a simplified next-generation sequencing library preparation method, the method comprising the steps of: providing a nucleic acid molecule; generating a transposome by binding a transposase and an external DNA having only one type of nucleotide sequence; mixing the nucleic acid molecule and the transposome to generate a fragmented nucleic acid molecule having both ends composed of the one type of nucleotide sequence; and generating a next-generation sequencing library by enriching the fragmented nucleic acid molecule with primers having different sequences.