A decontamination apparatus for a viewing window includes a cylinder and a rotating module disposed at one end of the cylinder. The rotating module is connected with a viewing window. The rotating module can be driven to rotate, which further drives the viewing window to rotate for removing dirt attached to the viewing window. Besides, a decontamination apparatus for a viewing window includes a cylinder connected with a viewing window and a rotating module disposed at one end of the cylinder. The rotating module is connected with a wiper in contact with the viewing window. The rotating module can be driven to rotate, which further drives the wiper to turn for removing dirt attached to the viewing window.