The invention provides a device for cleaning a contact surface on a PCB with a cleaning portion having a wiper. The cleaning device for the contact surface is fixed to the bottom face of a mode detection portion having sensing projections for sensing a signal by contacting the contact surface on the PCB. The device comprises a fixing part for fixing the cleaning portion to the loading means in one side, two elastic guards for protecting the elastic legs of the mode detection portion by being formed as an entity with the fixing part, and a wiper having a proper shape for connecting the above two elastic guards and for removing unwanted matters from the contact surface by contacting and sliding on the contact surface on the PCB against the bottom face. The wiper of the device for cleaning the contact surface removes unwanted matters from the contact surface while sliding the contact surface on the PCB, and thus prevents erroneous operation that can occur in case of detecting a signal with contacting the mode detection portion on the contact surface.