To easily conduct adjustment even in the case release timing of a feed roll is changed with respect to a roll type material feed device.

A feed roll 4 is mounted to one end of an oscillation arm 2 and a cam follower 3 to the other end, voltage is impressed between the release cam 1 arranged above the cam follower 3 of a material feed device and the cam follower 1, the contact of both is detected by the electric current flowing between both, by receiving a crank rotation position signal from a rotation position sensor 12 and arranging a sensor 9 to index a crank angle at a time of causing contact between the release cam 1 and the cam follower 3, the angle is displayed on a display device 10.