Adverb (fukushi), Na-adjective (keiyodoshi)
intently; single-mindedly; devotedly; solely; earnestly; with all one's heart
Usually written using kana alone
彼はひたすら成功を望んで懸命に働く。He works hard because he is anxious to succeed.
Also written 一向【ひたすら】、頓【ひたすら】