However, because of his strong belief as a Christian, he was viewed as a threat to the bakufu (Japanese feudal government), and since Shigekatsu himself did not conduct the domain duties, was indulged in debauchery, drove mad, murdered the father and son of the vassal, Shinzaemon OIKE who was remonstrating, and had many vassals commit suicide, the bakufu deprived his position, and he was handed down to Tadaharu HORIO.
しかしキリシタンとして熱心な信仰を行なっていたために幕府に危険視され、また茂勝自身も藩政を省みずに放蕩に耽り、終いには発狂して諫言をする家臣・尾池清左衛門父子を殺害、多くの家臣を切腹させた為に遂に幕府から改易を申し渡され、堀尾忠晴に身柄を預けられた。