TOKYO, March 18 (Reuters) - A U.S.-based fund has called for Japan's Shimizu Corp to halt a $190 million bid to take control of road builder Nippon Road Co Ltd, saying the deal would be unfair to minority shareholders and go against governance reform.

In a letter to Nippon Road's board this week that was seen by Reuters, Kaname Capital objected to Shimizu's bid to double its holding to 50.1%.

Kaname, which owns 1.8% of Nippon Road, said the deal would put minority shareholders at a disadvantage by turning them into investors in a listed subsidiary.

"A partial bid is unsatisfactory. Only a 100% bid allows for fair and equal treatment of all shareholders," the Boston-based long-only fund said in its letter.

The offer price of 10,000 yen ($84.13) a share was too low given Nippon Road's cash on hand, shareholdings and other assets, Kaname said, putting the share value closer to 12,500 yen. (Reporting by Makiko Yamazaki; Editing by David Dolan and Kim Coghill)