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* Big manufacturers' sentiment index +18 vs f'cast +13 - tankan

* Big non-manufacturers' sentiment improves slightly in Q3

* Big firms expect capex to increase 10.1% this fiscal year

By Tetsushi Kajimoto and Leika Kihara

TOKYO, Oct 1 (Reuters) - Japanese business confidence improved in the three months to September, a central bank survey showed on Friday, a sign the economy was steadily emerging from the slump caused by the coronavirus pandemic.

Large companies expect to increase capital expenditure by 10.1% in the current fiscal year ending in March 2022, the survey showed, backing up the central bank's view robust corporate-sector activity will offset some of the weakness in consumption.

The survey bodes well for Fumio Kishida, who will succeed Prime Minister Yoshihide Suga next week with a mandate to pull the economy out of the pandemic-induced doldrums and distribute more wealth to households.

The headline index gauging big manufacturers' sentiment stood at plus 18 in the third quarter, up from plus 14 in the previous quarter, the Bank of Japan's (BOJ) closely-watched tankan survey showed.

It compared with a median market forecast for plus 13.

Big non-manufacturers' sentiment index improved to plus 2 from plus 1 in June, against a median market forecast for a flat reading, the survey showed.

Big manufacturers expect sentiment to worsen three months ahead, it showed.

The survey will be among factors the BOJ will scrutinise when it meets for a rate review on Oct. 27-28 and revises its quarterly growth and inflation projections.

Robust exports driven by solid global demand have helped offset weak consumption and pull Japan's economy out from the severe slump last year caused by the pandemic.

But chip shortages and supply disruptions caused by Asian factory shutdowns have hit production of Japanese manufacturers, threatening to derail the country's fragile recovery.

The central bank will closely scrutinise the results of the tankan survey at its next policy-setting meeting on Oct. 27-28, when it gives projections for growth and inflation. (Reporting by Tetsushi Kajimoto and Leika Kihara; Editing by Sam Holmes)