The main goal of this study is to clarify the arc-characteristics with different surface and shape conditions and to acquire basic insights for designing way for appropriate electrode structure for arc blowing by arc guide with external DC magnetic field.Silver-tin-dioxide material is chosen as typical contact material.Different contact shapes are prepared: "R-type" (normal shape), "Rpolish" at which R-type is polished by sandpaper #2000, and "Rdeform" at which R-type is deformed so that contact has slope asymmetrically.Breaking waveforms and aspects are measured.Arc-duration in the "Rdeform" is shorter than for the "R-type" case.The measured aspects by high-speed camera indicate that the location of arc-column is moved to outside of contact following the slope, but the fluctuation between edge and center are also caused.These results are basic and useful finding and consideration to clarify not only the contact-breaking phenomena but also the design methodology of contact electrode.