BNZ economist Doug Steel said nationally, all firm size categories were moving forward, with production and new orders categories "leading the recovery charge, and the employment and restocking phase kicking in over recent months".
"There has been a marked turnaround from the terrible conditions of 12 months ago when firms were shedding labour and manufacturing firms of all sizes were contracting," Mr Steel said in a statement.
The BNZ-Business New Zealand performance of manufacturing levels above 50 indicate expansion, and below 50 contraction.
The result for April was the third consecutive month where all the main indices of production, new orders, employment, finished stocks and deliveries were in expansionary mode - above 50.
Nationally, the seasonally adjusted overall national index for April stood at 58.9, up 2.2 on March, while in Otago the April reading of Otago-Southland unadjusted PMI for April was down slightly to 53.4 points, Otago Southland Employers Association chief executive John Scandrett said.
"While this is down a little on the 57.5 reading in March, we are holding a positive line in overall terms," he said in a statement.
"It is pleasing to see that while the Otago and Southland manufacturing sector marginally trails the national trending pattern, our local survey outcomes are stable within a firm expansionary band."
The local region had seen positive results in the survey diffusion indices covering production, finished stocks and deliveries.
"From February this year, across these three categories there has been a continual improvement in the results," Mr Scandrett said.
Business NZ's executive director for manufacturing Catherine Beard, said the New Zealand results fitted well with global manufacturing data, with the JP Morgan Global PMI, the USA PMI and the Australian PMI all in "strong positive growth".
"The continued slow and steady expansion in the sector is finally flowing through to new jobs, which is good news for the unemployed and good news for the economy," Ms Beard said.
Mr Steel said it was encouraging the improvement was widespread across all components, industries, regions and firm-size categories.
"While there are still some negative comments in survey responses, the advancing manufacturing sector will certainly help offset patchiness or even outright weakness in some other parts of the economy," he said.
The unadjusted results by region showed all in expansion during April; led by Canterbury at 58.0, the Central region at 56.6, which was previously in contraction.
The Northern area stood at 54.3, while Otago/Southland was at 53.4.
