Tumor necrosis factor-${alpha}$ (TNF-${alpha}$) and inflammatory cytokines released from activated macrophages in response to particulate debris greatly impact periprosthetic bone loss and consequent implant failure. In the present study, we found that a major polyphenolic component of green tea, (-)-epigallocatechin gallate (EGCG), inhibited Ti particle-induced TNF-${alpha}$ release in macrophages $in$ $vitro$ and calvarial osteolysis $in$ $vivo$. The Ti stimulation of macrophages released TNF-${alpha}$ in a dose- and time-dependent manner, and EGCG substantially suppressed Ti particle-induced TNF-${alpha}$ release. Analysis of signaling pathway showed that EGCG inhibited the Ti-induced c-Jun N-terminus kinase (JNK) activation and inhibitory ${kappa}B$ ($I{kappa}B$) degradation, and consequently the Ti-induced transcriptional activation of AP-1 and $NF-{kappa}B$. In a mouse calvarial osteolysis model, EGCG inhibited Ti particle-induced osteolysis $in$ $vivo$ by suppressing TNF-${alpha}$ expression and osteoclast formation. Therefore, EGCG may be a potential candidate compound for osteolysis prevention and treatment as well as aseptic loosening after total replacement arthroplasty.