A deflection correcting device includes a banknote running passage formed by a first passage plate and a second passage plate, and a deflection correcting wheel is arranged inside the banknote running passage and has a deflection correcting direction deviated with respect to a reference wall of the banknote running passage. Multiple deflection correcting wheels are dispersedly arranged in a conveying direction of the banknote running passage and are arranged to gradually close to the reference wall. An adjusting wheel having a guide direction along a guide direction of the reference wall is provided at the position of the reference wall, and the adjusting wheel is arranged between a first deflection correcting wheel and a second deflection correcting wheel in the multiple deflection correcting wheels. A linear speed of rotation of the adjusting wheel is greater than a linear speed of rotation of the respective deflection correcting wheel.