Small-scale　samples　enable　us　to　understand　changes　in　physical　properties　under　larger　strain　due　to　their　higher　tolerance　to　deformation.　In　this　study,　the　piezoresistive　character　of　n-type　＜　111　＞-oriented　Si　nanowires　under　large　strain　was　measured　during　tensile　and　compressive　deformations.　The　Si　nanowires　were　directly　cut　from　the　wafer　using　top-down　technology　and　deformed　while　capturing　their　electrical　properties　inside　a　transmission　electron　microscope.　The　experimental　results　show　that　both　tensile　and　compressive　deformation　enhanced　their　electrical　transport　properties.　The　piezoresistance　coefficient　is　of　the　same　order　of　magnitude　as　its　bulk　counterpart,　but　half　as　large,　which　may　be　attributed　to　a　larger　strain　magnitude.　We　also　studied　the　circulatory　characteristics　and　influence　of　electron　beam　radiation.　This　study　provided　new　physical　insights　into　piezoresistive　effects　under　large　strain.