In order to specify the exposure environment of interior-originating cracks in very high cycle fatigue, crack growth tests with CT specimens were conducted in air, high vacuum (HV) and ultra high vacuum (UHV). Influence of vacuum environment on characteristics of fatigue crack propagation and fracture surfaces was investigated. As a result, the following were obtained. (1) difference of fatigue crack growth rate between HV and UHV was accounted for by ΔKeff, although difference between air and vacuum was not explained only by the crack closure, (2) Kop became larger when vacuum pressure decreased, (3) a few micrometer size granular region was observed on the fracture surface only in HV and UHV.