A review of ultra trace element analysis with total-reflection X-ray photoelectron spectroscopy (TRXPS) and its applications to the semiconductor surface are descrided. TRXPS is a method for improving the detection sensitivity by increasing the peak to background ratio for photoelectron spectrum. The detection limit of TRXPS was found to be 9×10¹⁰ atoms/cm² for contamination on Si wafers. The improvement is 40 to 100 times of the normal-type XPS.