Abstract: A paper cutter with a mold board has a base, an adjusting seat, a knife mount, a cutting knife, a bias spring, an adjusting nut, a positioning knob and a holding member. The cutting knife is secured to the knife mount pivotally secured to the adjusting seat. The bias spring is placed in a hole on the adjusting seat and housed in a cavity on the knife mount and retained by the adjusting nut in contact with the knife mount, permitting the cutting knife to be flexibly operated. The adjusting seat is secured to a guide groove of the base. The mold board has plural guide tracks on one side and anti-slip stickers on the other side. The base is slidably mounted to the mold board to make the cutting knife operate with ease, precision and stability.