The $eta$-xylosidase (EC 3.2.1.37) of Penicillium verruculosum was purified and characterized. Molecular weights of the enzyme were 200,000 dalton and 100,000 dalton as determined by gel filtration and SDS-gel electrophoresis, respectively. The optimum pH for the enzyme activity is 4.0 and it was stable in range of pH 3.0~6.0. The temperature optimum for the enzyme activity was $70^{circ}C$, and was stable up to at $60^{circ}C$ for 24 h. $K_m$ and $V_{max}$ of the enzyme on p-nitrophenyl-$eta$-D-xylopyranoside were 1.7 mM and 630 U per mg protein, respectively. The purified $eta$-xylosidase was inhibited noncompetetively by D-xylose and $K_i$ was 10 mM.