4 Nines (99.99%) Cd and Te were purified to the semiconductor grade 6 Nines ∼ 7 Nines purity materials by the distillation and the zone melting processes, in order to be used for the growth of CdTe single crystal. The CdTe single crystal of 100 mm in diameter and 18kg in weight was successfully grown by the traveling heater method (THM). The shape of the growth interface had the key role for the single crystal growth. The distribution of the Te inclusion size was measured by IR microscopy. The uniformity of mobility-lifetime products and energy resolution in the wafer were also evaluated. The CdTe X-ray flat panel detector (FPD) was developed using the THM grown CdTe single crystal wafer. The CdTe pixel detectors with 100 mm pixel pitch were flip-chip bonded with the C-MOS readout ASIC and lined up on the print circuit board to cover the active area of 77 mm × 39 mm. The evaluation results showed that the CdTe X-ray FPD is promising as the imager for the non-destructive testing.