Fine needle aspiration cytology and histological analyses provide remarkable precision and are used to obtain a definitive diagnosis of thyroid carcinoma. In order to improve the quality of life of patients, developing an early detection method, in addition to Papanicolaou staining, for diagnosing thyroid carcinomas is crucial. We herein demonstrate that optical spacer biotinylation of JT IgM antibodies (>900 kDa, pentamer), which detect sialylated fibronectin in thyroid cancers, and biotinylated antibodies can be used for fluorescent and enzymatic staining. We investigated the detectability of antigens in the SW1736 cell line and exfoliative cells obtained from a papillary carcinoma patient using two staining methods, phycoerythrin (PE) fluorescent and diaminobenzidine (DAB) enzymatic staining. The fluorescent staining method provided higher visibility of the antigens than conventional DAB enzymatic staining. Although Papanicolaou staining is required to make a definitive diagnosis of thyroid carcinoma, the fluorescent staining method is helpful for detecting thyroid carcinoma antigens rapidly and at a higher sensitivity. Moreover, the use of the biotinylation method of detecting high-molecular IgM will shed light on the utilization of IgM antibodies.