Dental noble alloys often contain copper (Cu). Eluted metal ions sometimes irritate oral tissues. The most eluted ions are Cu ions. The purpose of this study was to investigate the effects of low cytotoxic (IC90, 100 µmol/L) Cu ions on macrophages by proteome analyses consisting of two-dimensional (2D) electrophoresis and matrix-assisted laser desorption/ionization -time of flight (MALDI-TOF) mass spectrometry. The analyses revealed that stimulation with IC90 Cu ions for 1 day caused the macrophage to significantly increase five specific protein spots. Mascot peptide mass finger-print matching suggested that four of them were attributed to 70 kDa heat shock protein 1A/1B (HSP70). HSP70 expression was verified by expressions of corresponding HSPA1A and HSPA1B mRNAs of the macrophage in quantitative real-time PCR analyses. It was concluded that by producing abundant HSP70, the macrophage protected itself against intracellularly intruding cytotoxic Cu ions that might un-fold and crosslink cellular proteins.