A flexible printed board includes a base material, first conductive pads arranged along an imaginary line on the base material and extending with a first width from front end to rear end on a front side of the imaginary line, second conductive pads arranged along the imaginary line and extending with a second width from front end on a rear side of the imaginary line to rear end, first wiring patterns provided between the second conductive pads, and extending with a third width to front end connected to the rear ends of the first conductive pads, and a reinforcing layer for reinforcing a reinforcing area over the first conductive pads and the first wiring patterns, and having a front edge on a front side of rear ends of the first conductive pads and a rear edge on a rear side of the rear ends of the second conductive pads.