disclosed is a heat resistant alloy for exhaust valves , in which ni - content is constrained to at maximum 62 % due to the material cost , while the strength is maintained equal or better to those of conventional alloys and the strength is kept even after use at high temperature for a long period of time . the alloy has the composition essentially consisting of , by weight %, c : 0 . 01 - 0 . 2 %, si : up to 1 . 0 %, mn : up to 1 . 0 %, p : up to 0 . 02 %, s : up to 0 . 01 %, ni : 30 - 62 %, cr : 13 - 20 %, w : 0 . 01 - 3 . 00 %, mo : up to 2 . 0 %, provided that mo + 0 . 5 w : 1 . 0 - 2 . 5 %, al : 0 . 7 % or higher and less than 1 . 6 %, ti : 1 . 5 - 3 . 0 %, nb : 0 . 5 - 1 . 5 %, b : 0 . 001 - 0 . 010 %, provided that /: 1 . 6 or more to less than 2 . 0 , and the balance of fe and inevitable impurities . optional components are i ) at least one of mg : 0 . 001 - 0 . 030 %, ca : 0 . 001 - 0 . 030 % and zr : 0 . 001 - 0 . 100 %, ii ) cu : up to 2 . 0 %, and iii ) v : 0 . 005 - 1 . 00 %.