A steering control apparatus of a simple configuration is adaptable so as to construct a redundant system from an input to an output system at low cost in a reliable manner. In one embodiment, the knob is rotatable in a rotary degree of freedom and moveable in at least one transverse direction approximately perpendicular to the axis. When the control valve is shifted to a neutral state and a floating function mode is selected, a large chamber and a small chamber of the hydraulic cylinder are connected to each other by the double check valve. A first conductive spacer is formed along a first sidewall of the opening to define a PNP emitter region within the base region.