To provide a durable X-ray detector difficult to be broken by vacuuming or leakage to atmospheric pressure, and a surface analyzer including the same.

A X-ray detector 10 includes a detector case 11 having an opening 11a, a gas introduction port 11b, and a gas discharge port 11c, a window frame 14 having an opening 14a, a resin flat plate window material 12 held between the detector case 11 and the window frame 14 to be disposed between the opening 11a of the detector case 11 and the opening 14a of the window frame 14 and configured to transmit characteristic X rays, and a core wire 13 disposed in the detector case 11 to measure current, and is arranged in a sample analysis room where vacuuming and leakage to atmospheric pressure are enabled. The X-ray detector 10 includes a first metal mesh 17a and a second metal mesh 17b. Between the opening 11a of the detector case 11 and the opening 14a of the window frame 14, the first mesh 17a, the window material 12, and the second mesh 17b are arranged in this order to be held.