PURPOSE: To provide a horizontal linearity correcting circuit which can continuously and inexpensively control the horizontal S-shaped correction value without increasing the number of parts and then can prevent the distortions on a display screen.

CONSTITUTION: A horizontal linearity correcting circuit consists of a capacitor 6 connected in series to a horizontal deflecting coil 4, a power MOSFET 14 connected between the capacitor 6 and the ground, and a diode 15 connected in anti-parallel to the MOSFET 14. The conducting period of the MOSFET 14 is controlled from the start of horizontal deflection in accordance with the horizontal deflecting frequency. Therefore the S-shape correction value is continuously controlled. Furthermore the MOSFET 14 always conducts once per horizontal period in its operating state.