To provide an ink supply amount measuring device and a dampening water supply amount adjusting device in an offset printer.

In the offset printer, the ink supply amount measuring device includes: a stress sensor which is arranged on an ink key, and outputs a measurement value of the stress on the ink key; a measurement value storage unit for receiving and storing the measurement value; and a measurement value processing unit for determining whether the measurement value is within the predetermined range, and a dampening water supply amount adjusting device includes: a dampening water supply amount adjusting roller which is arranged near a dampening water supply fountain roller, and can rotate and move in a printing width direction; and a dampening water supply amount adjusting roller state switching unit which switches a separated state and a contact state of the dampening water supply amount adjusting roller, and performs position movement of the printing width direction according to the determination result of the measurement value processing unit.