A first object of the present invention is to provide a stretchable conductor sheet that exhibits isotropic conductivity when stretched in a predetermined direction or in a direction perpendicular to the predetermined direction, and a paste for forming a stretchable conductor sheet, which is used for the stretchable conductor sheet. A second object of the present invention is to provide a stretchable conductor sheet having a small change in specific resistance even when repeatedly twisted, and a paste for forming a stretchable conductor sheet, which is used for the stretchable conductor sheet. A third object of the present invention is to provide a stretchable conductor sheet having a small change in specific resistance even when repeatedly washed, and a paste for forming a stretchable conductor sheet, which is used for the stretchable conductor sheet. The first object of the present invention can accomplish a stretchable conductor sheet having a thickness of 3 to 800 μm, the stretchable conductor sheet comprising at least conductive particles, inorganic particles surface-treated with a hydroxide and / or an oxide of one or both of Al and Si, and a flexible resin having a tensile elastic modulus of 1 MPa or more and 1000 MPa or less, wherein in each of two orthogonal directions, a specific resistance change ratio of the sheet at a time of elongation by 40% with respect to an original length is less than ±10% in an elongation direction.