We propose a new electro-pneumatic on-off valve with a disk flapper (a step-disk combining two semicircular disks with different diameters) driven by a pulse motor. This on-off valve consists of a disk flapper and a nozzle. The PWM mode is the technique used for driving the pulse motor. At first, as a preliminary experiment to establish the characteristics of the disk flapper, an eccentric disk is set to the nozzle exit and it is rotated by a motor. The effects of the position, the width and the diameter of the disk and the eccentric length to the back pressure are examined. Then, it is shown that pneumatic pulses to drive an actuator (air cylinder) are generated by continuous clockwise and counterclockwise rotations of the pulse motor, and the characteristics are measured.