A straddle-type vehicle comprising: a front wheel and a rear wheel; an engine disposed between the front wheel and the rear wheel; and an air cleaner box (20, 20A, 20B) disposed above the engine; and a vehicle body behavior sensor provided on a periphery of the air cleaner box (20, 20A, 20B) and located above a bottom wall surface of the air cleaner box (20, 20A, 20B), wherein the vehicle body behavior sensor is attached and supported on the air cleaner box (20, 20A, 20B) characterized in that: the air cleaner box (20, 20A, 20B) has on an outer wall surface thereof, a recess in which at least a portion of the vehicle body behavior sensor is accommodated, the air cleaner box (20, 20A, 20B) includes a reinforcement structure which suppresses a vibration in a thickness direction of an upper wall surface on which the vehicle body behavior sensor is supported, the reinforcement structure includes a first plate member, a second plate member, and a third plate member, the first plate member is provided on a region of the upper wall surface of the air cleaner box (20, 20A, 20B), the region facing the vehicle body behavior sensor, wherein the first plate member is provided between a bottom wall surface of a body section of the vehicle body behavior sensor and a fastening surface of the recess, a plurality of ribs are provided in a region of an inner wall surface of the air cleaner box (20, 20A, 20B), the region facing in a vertical direction the fastening surface to which the first plate member is fastened, the second plate member and the third plate member are fastened to regions, respectively, which are in the vicinity of the vehicle body behavior sensor, the second plate member is fastened to a region of the upper wall surface of the air cleaner box (20, 20A, 20B), the region being leftward relative to the recess, and the third plate member is fastened to a region of the fastening surface, the region being rightward relative to the body section of the vehicle body behavior sensor. a front wheel and a rear wheel; an engine disposed between the front wheel and the rear wheel; and an air cleaner box (20, 20A, 20B) disposed above the engine; and a vehicle body behavior sensor provided on a periphery of the air cleaner box (20, 20A, 20B) and located above a bottom wall surface of the air cleaner box (20, 20A, 20B), wherein the vehicle body behavior sensor is attached and supported on the air cleaner box (20, 20A, 20B) characterized in that: the air cleaner box (20, 20A, 20B) has on an outer wall surface thereof, a recess in which at least a portion of the vehicle body behavior sensor is accommodated, the air cleaner box (20, 20A, 20B) includes a reinforcement structure which suppresses a vibration in a thickness direction of an upper wall surface on which the vehicle body behavior sensor is supported, the reinforcement structure includes a first plate member, a second plate member, and a third plate member, the first plate member is provided on a region of the upper wall surface of the air cleaner box (20, 20A, 20B), the region facing the vehicle body behavior sensor, wherein the first plate member is provided between a bottom wall surface of a body section of the vehicle body behavior sensor and a fastening surface of the recess, a plurality of ribs are provided in a region of an inner wall surface of the air cleaner box (20, 20A, 20B), the region facing in a vertical direction the fastening surface to which the first plate member is fastened, the second plate member and the third plate member are fastened to regions, respectively, which are in the vicinity of the vehicle body behavior sensor, the second plate member is fastened to a region of the upper wall surface of the air cleaner box (20, 20A, 20B), the region being leftward relative to the recess, and the third plate member is fastened to a region of the fastening surface, the region being rightward relative to the body section of the vehicle body behavior sensor. the air cleaner box (20, 20A, 20B) has on an outer wall surface thereof, a recess in which at least a portion of the vehicle body behavior sensor is accommodated, the air cleaner box (20, 20A, 20B) includes a reinforcement structure which suppresses a vibration in a thickness direction of an upper wall surface on which the vehicle body behavior sensor is supported, the reinforcement structure includes a first plate member, a second plate member, and a third plate member, the first plate member is provided on a region of the upper wall surface of the air cleaner box (20, 20A, 20B), the region facing the vehicle body behavior sensor, wherein the first plate member is provided between a bottom wall surface of a body section of the vehicle body behavior sensor and a fastening surface of the recess, a plurality of ribs are provided in a region of an inner wall surface of the air cleaner box (20, 20A, 20B), the region facing in a vertical direction the fastening surface to which the first plate member is fastened, the second plate member and the third plate member are fastened to regions, respectively, which are in the vicinity of the vehicle body behavior sensor, the second plate member is fastened to a region of the upper wall surface of the air cleaner box (20, 20A, 20B), the region being leftward relative to the recess, and the third plate member is fastened to a region of the fastening surface, the region being rightward relative to the body section of the vehicle body behavior sensor.