Tribo-charging characteristics on toner in a two-component developer are affected by various factors such as material component, shape, and methods of tribo-charging or measuring. It is, therefore, important to evaluate tribo-charging behavior in details under certain conditions. Tribo-charging on toner is performed by using a mixing shaker with arm length of 200mm. Rotation speed corresponding with shaking frequency is 150rpm and 180rpm. Charge quantity is measured by the E-SPART method. As toner sample, a negative yellow type of toner based on bisphenol A and polyester resin is used. From the experimental results, it is showed that the q/m dependence on shaking time is saturated at near 5min with a negative value of −20 μC/g. After 5min, the q/m decreases slightly to a constant value of −15 μC/g. Charge quantity on toner shows approximately a parabolic dependence on toner diameter in the region up to 10μm in the twocomponent developer. The charge quantity q on toner is shown to be limited by the upper value deduced from the discharge condition in air and the q at 10μm was about 6fC less than 8.35fC.