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TOKYO, Oct 31 (Reuters) - Denso Corp, Japan's largest auto parts maker, said on Thursday its first-half operating profit rose 17.4 percent, thanks to steady sales of air-conditioners and strong output by top shareholder Toyota Motor Corp .
Denso, 24.5 percent owned by Japan's largest automaker, said group operating profit totalled 80.10 billion yen ($651.5 million) for the six months that ended in September. Group revenues rose 4.9 percent to 1.14 trillion yen.
Denso saw net profits rise 181.3 percent for the half year to 106.47 billion yen, thanks in large part to a one-off profit of 112.2 billion yen from altering the management of employee pensions.
Toyota, also Denso's biggest customer, reported on Wednesday its best-ever operating profit for any half year, driven by healthy North American sales, cost-cutting and a softer yen.
Denso's aggressive expansion into overseas markets, including North America and Southeast Asia, helped to drive up demand for parts.
The company has made significant progress in selling its air-conditioning systems to non-Japanese automakers including General Motors Corp , Volkswagen AG and Ford Motor Co .
Denso's margins are also improving as it has sought to reduce fixed costs by making parts compatible with numerous models.
For the full year to March, the company slightly raised its net profit forecast to 146 billion yen from a May forecast of 145 billion yen. It upped its full-year group revenue forecast to 2.24 trillion yen from 2.20 trillion yen.
The announcement came after the close of morning trading on the Tokyo stock market. Shares of Denso rose 1.28 percent to 1,978 yen, compared with a 1.11 percent fall in the Nikkei average . ($1=122.93 yen)