A coil-integrated switching power supply module that provides an improved heat radiation effect to keep the temperature of the entire coil-integrated switching power supply module to a lower value includes a thermal diffusion conductor pattern arranged around a hole through which a magnetic core extends on a layer. The thermal diffusion conductor pattern continuously extends in areas where coil conductor patterns are located on other layers and outside areas where the coil conductor patterns are located on the other layers. In addition, the thermal diffusion conductor pattern includes slits at portions thereof and does not define a closed loop around the hole through which the magnetic core extends.