A pressure sensor includes a surface sheet whose front side is an operating surface and a substrate sheet that includes a plurality of switches and that is disposed below the back side of the surface sheet at a predetermined space therebetween. When the operating surface is depressed, the surface sheet is deformed toward the substrate sheet and a switch of the plurality of switches is turned into an input state, and a resolution of a switch signal from each of the switches varies in accordance with the amount of a pressing force applied on the operating surface. Therefore, an electronic device, such as a cellular phone, installed with the pressure sensor can have various functions realized by a variation in the resolution.