The nanostructured functionally graded material (Nano-FGM) is one of the most promising materials for engine components. Nanocrystalline functionally graded material was composed of 3 weight percent yttria stabilized zirconia (YSZ) powder layer, mixed powder layers of the zirconia and SUS410L (similarly to AISI410) stainless steel and the stainless steel powder layer. It was consolidated by spark plasma sintering process that makes possible sintering at a low temperature because on-off pulse electric current causes melting and evaporation on an oxidized and contaminated surface of powder particles without ordinary heating the particle interior during the consolidation of the powders. Tensile tests were made at room temperature in the composition-graded direction of the multi-layer bulk FGMs 50 mm in diameter and 17 mm in thickness. In the FGMs composed of the stainless steel powders 9 mum in diameter including 63 nm size crystal grains and the YSZ powders 50 mum in size including 35 nm size crystal grains, the tensile strength was increased from 61.9 to 110 MPa and from 30.5 to 109 MPa with increasing from 19.6 to 39.2 N/mm(2) at a sintering die temperature of 1243 and 1293 K. In the FGMs composed of the stainless steel powders 60 mum in size including 52 nm size crystal grains and YSZ powders 50 mum in diameter including 35 nm size crystal grains, the tensile strength was increased from 37.5 to 71.9 MPa and from 53.4 to 76.1 MPa with increasing from 19.6 to 39.2 N/mm(2) at a sintering die temperature of 1243 and 1293 K. It was found that the tensile strength must depend on the size of powders.