To provide a polishing pad which can accurately and stably measure a film thickness by an optical sensor and which can prevent a material to be polished from being scratched.

The polishing pad 10 comprises an upper layer pad 11, having a window hole 11a formed to dispose a transparent window member 41 for transmitting light, and a lower layer pad 12 having a light-passing hole 12a to communicate with the hole 11a of the pad 11. The pad 10 further comprises a transparent adhesive film 13, coated on upper and lower surfaces with adhesives and disposed between the pad 11 and the pad 12. Sizes of the hole 11a of the pad 11 and the hole 12a of the pad 12 are formed substantially the same.