One in five also admitted that they would be less likely to employ someone if they knew they had a history of mental illness.
Almost three in five believed that stress did not qualify as a reason for sick leave, with 64 saying the same about anxiety.
1,800 employers took part in the survey, which was conducted by online therapy and coaching company Mentaline.
39% said they "struggled" to take mental health seriously.
Jesper Buch, founder of Mentaline.com, said, "Many of these issues can actually stem from working environments; so it’s important that employers acknowledge the problems, and fully understand them. As for employers being less in favour of hiring people with a history of mental health, that is discrimination, and in most cases is against the law."
