Royal College of Nursing (RCN) director Janet Davies told the BBC the findings were "very concerning but not surprising - we have been hearing about this for some time from nurses".
She added: "What we are finding is the pressures, particularly in hospitals and community areas, are getting greater as we have got more patients who are sicker coming through the system.
"We are seeing nursing posts frozen or cut in order to try and balance the books, it's obviously something we have been looking at for some time."
A Department of Health statement has responded to today's Nursing Time survey and its findings that suggest more than half of nurses think their ward or unit is dangerously understaffed.
– Department of Health spokesperson
There are more clinical staff working in the NHS now than there were in May 2010, and nearly 2,500 new nurses started working in NHS in October 2012 alone.
Hospitals are in charge of setting staffing levels but nursing leaders have been clear that they should publish staffing details and the evidence to show the numbers are right and safe for the services they deliver.
We are working with the sector skills councils, unions and employers to develop minimum training standards and a new code of conduct for health support workers.
The majority of respondents to the Nursing Times survey also said the ratio of patients to each nurse at their hospitals could compromise patient care.
More than eight out of 10 respondents said staffing on general medical wards in an acute hospital was at a ratio of eight patients to one nurse, or more.
And of these nearly half (44%) said the ratio was 10 or more patients per nurse.
A ratio of eight or more patients per registered nurse is associated with patient care on a ward regularly being compromised by short staffing, according to the Royal College of Nursing (RCN).
More than half of nurses think their ward or unit is dangerously understaffed, a Nursing Times survey revealed today.
Nearly six out of 10 (57%) described their ward as sometimes or always "dangerously understaffed", the research showed.
Over three quarters (76%) said they had witnessed "poor" care in their ward or unit over the past year - of which nearly 30% said they see poor care regularly.
Ahead of the the publication of the public inquiry report into deaths at Mid Staffordshire Hospital, the magazine polled 600 of its readers across a range of issues including staffing, patient safety and NHS culture.