A multigas sensor (200A) including a gas sensor element (100A) extending in an axial direction (O) and having an NO x sensor portion (30) and an ammonia sensor portion (42); a metallic shell (138); and a closed-bottomed tubular protector (141) having gas introduction holes (143a) formed in its side wall (143d), and a gas discharge hole (143b) formed in its front end wall (143t). At least a subportion of the ammonia sensor portion (42) is disposed within a positional range along the axial direction (O) between the gas introduction holes (143a) and the gas discharge hole (143b). The shortest distance (d1) between the gas introduction hole (143a) and the ammonia sensor portion (42) is shorter than the shortest distance (d2) between the gas introduction hole (143a) and the gas diffusion hole (8a).