The six stores with three in Auckland - the CBD, Botany and Albany - and one each in Wellington, Hamilton and Tower Junction in Christchurch.
As a result of the closures, around 70 people will lose their jobs.
Wilson said he had received many messages of support from loyal customers, and people had been shocked at the announcement.
"We've had customers who have been buying from us for over 40 years so we'd like to say thank you for all their support and we are sorry we are closing."
Ernest Munns set up shop in Christchurch at the end of World War I in 1918 after an unsuccessful search for work.
The chain had survived the years of the Great Depression in the early 1930s and the devastation of the Christchurch quake in 2011.
Carol Smith took over managing the business in 1927 after Munns died and formally bought the company in 1940.
Smith expanded Munns when he added a tailoring workshop and then the Suit Hire in 1965.
After 60 years of running the business, Smith retired and handed the reins to Barry Souter.
In 2002, Smith saw an opportunity to spread its wings to the North Island and purchased the Hugh Wright stores in Queen St, Auckland and Willis St in Wellington.
In February 2011, the company's head office and Armagh St store suffered the destruction of the Christchurch earthquake.
No staff were injured but due to the damage to the building the business moved to Tower Junction in Addington.
Souter retired later that year and Wilson took over.