A micro Polymerase Chain Reaction (PCR) chip, comprising:
- a reaction chamber having an opened upper surface intended to receive a fluid;
- and a cover intended to seal the reaction chamber, the cover comprising a light-transmitting portion of a light transmitting material which is faced with the opened upper surface of the PCR reaction chamber to close the open upper surface, the light-transmitting portion having a protruding part that extends toward the interior of the reaction chamber from regions of closed surfaces faced on the opened upper surface of the chamber, and the end of the protruding part being adjacent to or in contact with the surface of said fluid, wherein the protruding part of the light-transmitting portion is located in an optical path between a light-emitting module and a light-detecting module for detecting optical signals in said fluid.