A sensor device where the number of components and mounting steps can be reduced and mountability on a mounting target is improved. A sensor device configured to detect a torque applied to a pinion shaft and pinion shaft's rotation angle. The pinion shaft is formed by coupling an input shaft and output shaft together by a torsion bar. The sensor device includes a torque detecting portion wherein magnetic fields detected by torque detection magnetic sensors change based on the torsion bar's twisting amount, a rotation angle detecting portion wherein magnetic fields detected by rotation angle detection magnetic sensors change based on the pinion shaft's rotation angle, a housing that houses the torque detecting portion and the rotation angle detecting portion, and a circuit board held by the housing. Both the torque detection magnetic sensors and the rotation angle detection magnetic sensors are mounted on the circuit board.