A particulate matter sensor detecting particulate matter in exhaust emissions is provided, which is resistant to having sensor surfaces buried by particulate matter residue. Detection electrodes are provided, with alternating polarity, laminated in a laminating direction, separated by insulation. Of the detection electrodes, first detection electrodes of one polarity and second detection electrodes of the other polarity are exposed perpendicular to the laminating direction. In the direction perpendicular to the laminating direction, the particulate matter sensor has target accumulating parts on which the particulate matter is accumulated. In the target accumulating parts, the thickness W1 of the first detection electrodes in the laminating direction is greater than the thickness W2 of the second detection electrodes in the laminating direction.