A rotational angle sensor and a method for manufacturing the same, and a throttle control device with a rotational angle sensor, which may lower the cost, are provided. The rotational angle sensor includes each sensor IC 50(1), 50(2) for detecting a rotational angle of a rotor based on a magnetic field generated between a pair of magnets respectively disposed across the rotational axis of the rotor; each main terminal 61, 62, 63, 64 connected with each connection terminal 55, 56, 57 of each sensor IC 50(1), 50(2); and a holder member 90 for holding each sensor IC 50(1), 50(2) and connection portions of each main terminal 61, 62, 63, 64 on each sensor IC 50(1), 50(2) side. A sensor assembly 100 is constructed to form the sensor ICs 50(1), 50(2), the main terminals 61, 62, 63, 64 and the holder member 90 into an assembly. A potting material 102 is potted into the holder member 90.