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α-Neoagarobiose (NAB)/neoagarooligosaccharide (NAO) hydrolase plays an important role as an exo-acting 3,6-anhydro-α-(1,3)-L-galactosidase in agarose utilization. Agarose is an abundant polysaccharide found in red seaweeds, comprising 3,6-anhydro-L-galactose (AHG) and D-galactose residues. Unlike agarose degradation, which has been reported in marine microbes, recent metagenomic analysis of <i>Bacteroides plebeius</i>, a human gut bacterium, revealed the presence of genes encoding enzymes involved in agarose degradation, including α-NAB/NAO hydrolase. Among the agarolytic enzymes, <i>Bp</i>GH117 has been partially characterized. Here, we characterized the exo-acting α-NAB/NAO hydrolase <i>Bp</i>GH117, originating from <i>B. plebeius</i>. The optimal temperature and pH for His-tagged <i>Bp</i>GH117 activity were 35 °C and 9.0, respectively, indicative of its unique origin. His-tagged <i>Bp</i>GH117 was thermostable up to 35 °C, and the enzyme activity was maintained at 80% of the initial activity at a pre-incubation temperature of 40 °C for 120 min. <i>K_m</i> and <i>V_max</i> values for NAB were 30.22 mM and 54.84 U/mg, respectively, and <i>k_cat/K_m</i> was 2.65 s⁻¹ mM⁻¹. These results suggest that His-tagged <i>Bp</i>GH117 can be used for producing bioactive products such as AHG and agarotriose from agarose efficiently.