TOKYO (Reuters) - The Nikkei average was almost flat on Monday, as sharp falls in Advantest and Honda Motor following disappointing earnings results offset gains in trading companies such as Mitsui & Co.

The market erased earlier gains as investors remained cautious before more earnings reports due in both the United States and Japan and a raft of important economic data.

"Those who bought stocks this morning turned around and saw nobody following them, and they are closing their positions to lock in profits," said Fumiyuki Nakanishi, group manager of the investment information department at SMBC Friend Securities.

"Investors don't want to get deeper into buying ahead of the jobs data and ISM this weekend," he said, referring to the U.S. payrolls report for July and the Institute for Supply Management's July reading on U.S. manufacturing, both due on Friday.

As of 5:29 a.m. British time, the benchmark Nikkei was up 6.46 points at 13,341.22, after rising as high as 13,468.94. The broader Topix was nearly flat at 1,298.18.

The market rose in the morning as a softer yen and easing fears about the U.S. economy helped boost investor confidence, sparking short-covering in trading firms like Mitsui & Co.

Mitsui & Co rose 5.5 percent to 2,225 yen and rival Mitsubishi Corp gained 3.3 percent to 3,160 yen. A recent fall in oil prices had put selling pressure on these trading houses, which have stakes in overseas oil fields.

But the gains were pared by sharp falls in firms that have reported disappointing results.

Chip-tester maker Advantest, which posted a quarterly loss on slumping sales and orders, slid 7.4 percent to 2,140 yen. Honda, which cut its annual profit and global car sales forecasts, fell 4 percent to 3,610 yen.