An image sensor and a banknote processing apparatus are provided. The image sensor includes a first photosensitive assembly and a first light source assembly which is configured to irradiate light to an original, and further includes a first lens array configured to aggregate light reflected by the original to the first photosensitive assembly, and a light-entering surface of the first lens array is located in a transmission path of reflected light generated due to specular reflection occurred when light emitted from the first light source assembly irradiates on the original. According to different image grayscale values generated by the image sensor, the banknote processing apparatus judges whether a banknote surface is stuck to an adhesive tape.