Civil service minister Ingrid Yeung on Monday described a staff shortfall as "unsatisfactory", but said the authorities are trying hard to retain and recruit more staff.
According to a paper submitted to Legco, about 10,000 civil servants left their job in the 2022-2023 financial year, accounting for 5.7 percent of the workforce.
More than half of them retired.
Yeung said there's now a shortfall of 18,000 staff.
But with a projected drop in the number of retirees, the secretary for the civil service said the natural wastage rate will decline over time.
Meanwhile, more than 3,800 civil servants resigned in the past year, the highest figure in almost 30 years.
That represented a resignation rate of 2.2 percent, similar to that of 2021-2022.
"If you look at 2018 and 2019, the resignation rate was only 0.5 percent. But for this year and last year, it was over 2 percent," Federation of Trade Unions lawmaker Dennis Leung said.
Yeung said many of those who resigned were younger workers who prefer having different work experiences instead of sticking to one job.
She also said the authorities are working hard to recruit more civil servants, and her bureau has set an example to shorten recruitment time.
"For some grades, they take almost a year to complete one recruitment cycle. For those who want to join the civil service, they might have already been employed elsewhere," she said.
"We've asked departments to speed up the recruitment process. The Civil Service Bureau has set an example. Like for clerical grades, it took them at least 10 months to recruit. But after conducting year-round recruitment, it takes only three to four months now."