A stable, high-speed, high-efficiency constant voltage is provided without a complicated, large-scale, high-cost phase compensation circuit over a wide range of operating conditions. This voltage buck-boost switching regulator consists of a pair of voltage reducing transistors, a pair of voltage boosting transistors, inductance coil, output capacitor and controller. The controller has the following parts for performing PWM control of constant voltage for voltage reducing transistors and voltage boosting transistors: an output voltage feedback circuit, an inductor current sense circuit, a variable sawtooth wave signal generator, switching controllers, and a voltage boosting driver.