Mind Cymru says older men are more prone to suicide than younger adults, but many do not receive the support and medical guidance they need.
Its figures show that one in four have symptoms of depression, severe enough to warrant intervention.
Men with mental health problems have formed a support group to help others in Tondu, near Bridgend.
Ruth Coombs, Mind Cymru's manager for influence and change, believes that older men suffering from mental health problems often slip through the net.
"We know that when you get older you may retire, you may get made redundant and not work again, and that can be very difficult," she said.
"You get that sense of isolation, you may lose your social groups.
"Also, you may experience a loss of income, a loss of physical ability and if men lose their partner they're losing another protective factor around their mental health.
"So men do need to be supported."
In Tondu, a group of about 25 older men with mental health problems have formed a support project called Squirrels Nest.
Alan Roach, 67, who is one of the founder members, said there was little support locally catering for older men with mental health issues.
"We all have days when we go back into recession, as we say. But being here, it helps," he said.
"It's when you don't have anything to do or anywhere to go - that's when your mind starts wandering.  And when it starts wandering you know you're going bad again."
A charity is warning that more needs be done to help older men in Wales who are suffering from mental health problems.