A crosslinked elastomer body is composed of an electrically conductive composition comprising an electrically conductive filler and an insulative elastomer (matrix). The electrically conductive tiller is in a spherical particulate form and has an average particle diameter of 0.05 to 100 μm. The electrically conductive filler has a critical volume fraction (φc) of not less than 30 vol % as determined at a first inflection point of a percolation curve at which an insulator-conductor transition occurs with an electrical resistance steeply reduced when the electrically conductive filler is gradually added to the elastomer. A resistance observed under compressive strain or bending strain increases according to the strain over a resistance observed under no strain when the electrically conductive filler is present in a volume fraction not less than the critical volume fraction (φc) in the composition.