PURPOSE: To obtain a sheet material cutting device installed with an overload preventing structure which is small and has less power loss by elastically interposing a shaft in the groove provided on a driving connection lever.

CONSTITUTION: At the time when a load is abnormally increased at a cutter part for the reason of jamming, etc., a shaft groove 10 interposing the arm axis 4 at the tip of the driving arm 3 of a connection lever 8 is elastically opened and the arm axis 4 comes off into the slit groove 9 of the connection lever 8. The rotation of a motor side thereafter is not transmitted to a movable blade 1 because of the arm axis 4 being slided in the slit groove 9 of the connection lever 8. On reaching of the rotation position of a rotor 6 to the return stage, the arm axis 4 starts to rotate the driving arm 3 in the return direction, the driving arm 3 is stopped with the contact with the locking part 11 provided at the position where its movable blade 1 does not become in the state of its opening more than the original; stand by position and this driving mechanism is returned to the original stand by state, with the rotation of the rotor 6 pushing back the arm axis 4 to the position of the shaft groove 10.