A multigas sensor (200A) includes a multigas sensor element portion (100A) having: a NOx sensor portion (30A) which detects the concentration of NOx; and first and second ammonia sensor portions (42x, 42y) having different ratios between a sensitivity of ammonia and a sensitivity of NOx. The multigas sensor element portion has a plate-like shape which extends in the direction of the axis O. A temperature detecting portion (6) used for controlling the temperature of the NOx sensor portion is disposed in the multigas sensor element portion. The first and second ammonia sensor portions are disposed on the outer surface of the NOx sensor portion so that at least parts of the first and second ammonia sensor portions overlap with a first region (6s) which is defined in the width direction by ends in the axial direction of the temperature detecting portion.