A gyro horizon with laterally inclined axis can prevent the occurrence of the turning errors when the condition y₀=αV/g is atisfied, y0 being the lateral inclination of the gyro axis, V the flyng speed of the airplane, α the precessional speed due to the pendulosity of the gyro system, g the acceleration of gravity. The electrically driven gyro horizon constructed by this principle was examined theoretically and tested in the laboratory and showed very small turning errors. The pendulosity of the gyro system was 60 gr-cm and 105 gr-cm, longitudinally and laterally respectively. y°=10', α=0.0234(rad/sec), v=73.1(m/s)=263(km/h) are the values satisfying the turning error preventhing condition for the inclined axis gyro horizon. The flying speed of the airplane could be increased indefinitely if the special alternating current generator whose frequency is proportional to the flying speed is used for the rotation of the gyro.