Most do not seek help.
The NOP survey for Bella magazine shows that 4% of men nationwide and 10% of Londoners believe they suffer from "post natal depression".
The symptoms include tiredness, irritability and loss of libido.
Health experts say the condition has long been ignored.
Extra burden
Steve Jamieson of the Men's Health Forum said it was only just being recognised.
He added that many men felt rejected by their partner who was engrossed in the child.
They also feel worried about the sudden extra responsibility and financial burden.
"For men who are fathers for the first time, it can be a big, big shock.
"They often do not think about it when their partner is pregnant. It is more of a shock than for the woman as they have nine months to prepare.
"Men's role only really begins when the baby is born."
He added that some men suffered loss of sexual desire after the birth.
Most had witnessed the birth and found it offputting.
Mr Jamieson said health workers were beginning to respond to the problem, but he said more needed to be done.
He said the government's recently announced plan to get health visitors to promote good parenting would help if they insisted on seeing both parents after the birth and were more aware that fathers could have problems.
Ante-natal classes
He added that the subject of male depression needed to be discussed at ante-natal classes so that men would know what they were suffering from if they developed the condition.
The problem is made worse by the fact that many men do not talk about their problems and would not go to their GP if they were suffering from depression.
In the Bella survey, only just over half had sought help from their GP.
Mr Jamieson said the problem had begun to be recognised because men were becoming more involved in childbirth and parenting.
"Healthcare services need to take male depression following childbirth more seriously and recognise the changing role of men in the family," he said.
At least one in 10 women are thought to suffer from post natal depression, which can be very severe.
The causes are not clearly understood, but risk factors are thought to include isolation, poor emotional support, too much support, depression in pregnancy, having intervention in childbirth or a Caesarian section and difficult social and financial circumstances.
Background Briefings
Medical notes
Royal College of Nursing
National Childbirth Trust
Post natal depression
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