Prime Minister Scott Morrison doesn't think the departure of three government ministers at the next election will hurt the Coalition's chances of being returned to office.

Indigenous Affairs Minister Nigel Scullion, 62, on Saturday became the latest to announce he will be standing down, believing it's simply time for him to go after being in Parliament since 2001.

Prime Minister Scott Morrison says MPs' reasons for leaving should be taken at face value. Credit:AAP

That came after Perth-based Human Services Minister Michael Keenan revealed on Friday evening he wouldn't be running again, in order to spend more time with his wife and four children aged between six months and seven.

Opposition Leader Bill Shorten says the retirement announcements shows the "government was barely limping to the end of its term".