Exhaust gas purification catalyst

An exhaust gas purification catalyst comprising a substrate and a catalyst coating layer formed on the substrate, wherein:

• the catalyst coating layer comprises catalyst particles, the catalyst coating layer having an upstream region extending by 40 to 60% of the entire length of the substrate from an upstream end of the catalyst in an exhaust gas flow direction and a downstream region corresponding to the remainder portion of the catalyst coating layer, the composition of the catalyst particle of the upstream region being different from that of the downstream region;
• in the upstream region of the catalyst coating layer,
• an average thickness of the coating layer is in a range from 25 μm to 160 μm,
• a porosity measured by a weight-in-water method is in a range from 50 to 80% by volume, and
• high-aspect-ratio pores having an aspect ratio of 5 or more account for 0.5 to 50% by volume of the whole volume of voids, and
• the high-aspect-ratio pore has an equivalent circle diameter of from 2 μm to 50 μm in a cross-sectional image of a catalyst coating layer cross section perpendicular to an exhaust gas flow direction and has an average aspect ratio of from 10 to 50.