A bill handling machine includes a machine body 10 for conveying bills 3 and storing bills other than a bill 3 to be discharged and a detachable box 20 having a mounted section 21 detachably mounted to a mount section 11 of the machine body 10 for storing and discharging the bill 3 to be discharged. The machine body 10 includes distinguishing device (14b and 14c) for distinguishing whether or not the bill 3 is a dischargeable bill, conveying device 12 for conveying the bills 3 in the normal or reverse direction between the distinguishing device and the mounting section 11, and a keeping bill storage section 15 for storing the bills 3 other than the bill 3 to be discharged which is conveyed by the conveying device 12. The detachable box 20 includes a dischargeable bill storage section 25 for storing the bill 3 so as to be discharged.