Disclosed is an apparatus for detecting steering angle in vehicle, such that the size of the apparatus for detecting steering angle in vehicle using gears and magneto resistive sensors, could be reduced. An apparatus for detecting steering angle in vehicle including: a shaft gear axially combined to a steering shaft of a vehicle; a first detecting gear joined, with a first gear ratio, to the shaft gear in a tooth combining manner; a second detecting gear joined, with a second gear ratio, to the shaft gear in a tooth combining manner; a first permanent magnet installed on an axis of the first detecting gear, for generating rotational magnetic field; a first magneto resistive sensor closely installed on an upper portion of the first permanent magnet, for detecting rotational angle of the rotational magnetic field; a second permanent magnet installed on an axis of the second detecting gear, for generating rotational magnetic field; a second magneto resistive sensor closely installed on an upper portion of the second permanent magnet, for detecting rotational angle of the rotational magnetic field; and a computing/controlling means for computing rotational direction and angle of the steering shaft by processing detected signals provided from the first and the second magneto resistive sensors using a predetermined program, the apparatus is configured such that: the shaft gear is a multi-level gear having an upper level gear and a lower level gear; the first and the second detecting gears are joined to the upper level gear and the lower level gear in a tooth combining manner so that the first and the second detecting gears are partially overlapped; and a gap maintaining member for equally maintaining a gap between the second permanent magnet and the second magneto resistive sensor as much as a gap between the first permanent magnet and the first magneto resistive sensor, is further included.