A voltage conversion device includes: first and second loop circuits having a common inductance element. Electric current alternately flows through the first or second loop circuit as a first switching element of the first loop circuit is turned on or off. A magnetic field that is formed when the first switching element is turned on and that penetrates through the first loop circuit and a magnetic field that is formed when the first switching element is turned off after it is turned on and that penetrates through the second loop circuit have the same direction. All elements that constitute the first and second loop circuits are arranged on the same surface of a substrate. The second loop circuit is connected to a second direct-current power source. The first loop circuit is connected to a first direct-current power source.