An object of the present disclosure is to determine whether or not a codeword in which a plurality of symbol errors are corrected occurs, and to detect a potential network failure. According to the present disclosure, there is provided a network test apparatus including: a reception unit that receives codewords generated by using pulse amplitude modulation (PAM); an arithmetic processing unit that measures the number of symbol errors per codeword included in the codewords by using forward error correction (FEC), and counts the number of codewords for each number of symbol errors per codeword; and a display unit, in which whether or not there is a codeword in which a plurality of symbol errors are corrected is displayed on the display unit by using the number of codewords.