TOKYO, Oct 24 (Reuters) - Japanese electric motor maker Nidec Corp on Monday posted a 16% rise in second-quarter operating profit, missing analysts' estimates.

It reported 51.71 billion yen ($347.21 million) in operating profit for the three months to end-September, versus an average 52.3 billion yen profit estimated by five analysts, according to Refinitiv data.

A year earlier, the company earned 44.59 billion yen. ($1 = 148.9300 yen) (Reporting by Satoshi Sugiyama Editing by Chang-Ran Kim)