Metastasis is one of the major causes of cancer-associated mortality. Aberrant expression of matrix metalloproteinase-9 (MMP-9) has been implicated in the metastasis of various cancer cells. The aim of this study was to investigate the inhibitory effect of a glycoprotein (38 kDa) isolated from Styrax japonica Siebold et al Zuccarini (SJSZ) on metastasis of hepatocellular carcinoma (HCC) in diethylnitrosamine (DEN)-treated imprinting control region (ICR) mice. To study the chemopreventive effect of SJSZ glycoprotein on the metastasis of HCC, ICR mice were injected intraperitoneally with DEN (75 mg/kg) for 11 weeks. Subsequently, we evaluated nitric oxide (NO), alpha-fetoprotein (AFP), activator protein (AP)-1, cyclooxygenase (COX)-2, inducible nitric oxide synthase (iNOS), matrix metalloproteinase (MMP)-9, and interleukin (IL)-6 using biochemical reaction, immunoblot analysis, and reverse-transcription polymerase chain reaction. Here, the results showed that SJSZ glycoprotein (10 mg/kg body weight) reduced the production of NO in DEN (75 mg/kg)-treated ICR mice. Also, it suppressed the activity of AFP, AP-1 (c-Jun and c-Fos), COX-2, iNOS, and MMP-9. Taken together, SJSZ glycoprotein inhibits the activity of MMP-9 as a metastasis factor.