noun
humanly possible; work of man; human feat
Almost always used with a negative verb to say something is beyond human ability or not humanly possible.
これは人間業じゃない。
This is not humanly possible.
彼の演技は人間業とは思えない。
His performance doesn't seem like something a human could do.
神業 means 'divine work' or 'godlike feat', often used positively for an amazing human achievement, while 人間業 is used negatively to say something is beyond human ability.
Compound of 人間 (human) and 業 (work, deed).