The most allegations were made at Waikato's Springhill Prison. A man and a woman were dismissed for inappropriate relationships and three resigned in the nine-year period.
Corrections Association spokesman Beven Hanlon said the numbers were encouraging given that more than 4000 guards worked for the Department of Corrections.
"I'm surprised that number isn't higher, to tell you the truth. Obviously we would rather it was zero."
Since 2008, the number of allegations had dropped and remained steady, aside from a spike in 2013.
This year to the end of May, three staff had been accused of inappropriate relationships.
Mr Hanlon said the association had been working on initiatives to improve the calibre of people hired to work in jails and encouraging staff to speak up against people or behaviour they felt was inappropriate.
He said when it came to inappropriate relationships, it was more likely for staff to be involved with prisoners for financial gain rather than for sexual purposes.
Activities such as guards delivering messages between inmates and outsiders and bringing in contraband were more common than sexual relationships.
"In terms of physical relationships ... it's usually a female officer sleeping with a prisoner rather than a male officer [doing so]. We had more of a problem with this a few years back."
While the statistics were not high given the prison population - 8641 as at December 31 - they showed how some staff could "fall into" relationships with inmates, Mr Hanlon said.
Corrections spokesman Vincent Arbuckle said the department demanded a high standard of conduct, and staff were expected to have "role-model positive, law-abiding behaviour" ...
"The overwhelming majority of our staff fulfil their duties with integrity and commitment, in what is often a pressured and challenging environment."
New initiatives have been introduced to support the high standards of conduct expected from staff, including:
• More pre-employment checks, including integrity and conflict of interest questions.
• Credit checks for staff who will have significant financial responsibility in their role.
• An integrity committee.
• Code of conduct revised.
• An 0800 number for staff to get confidential advice and support and to report workplace wrongdoing.
• Drug testing for staff.
By the numbers
• 62 staff investigated
• 15 at women's prisons
• 47 at men's prisons
• 10 dismissed
• 14 warned
• 14 resigned
• 6 suspended, cautioned or otherwise dealt with
• 18 - no supporting evidence.
