RBC's Canadian Manufacturing Purchasing Managers' Index came in at 53.5 in December, a four-month low but still relatively strong.
Any reading above 50.0 is an indication of expansion.
The December index was down 1.8 points from 55.3 in November and down from 55.6 in October, which marked a 30-month high for the index. The last time the index fell below December's reading was in August, when it was 52.1.
"While output and new order growth ebbed in December following a particularly strong month in November, Canada's manufacturing sector continued to grow, registering a solid 53.5," said Paul Ferley, RBC's assistant chief economist.
RBC publishes the index in partnership with the Supply Chain Management Association and Markit, which compiles similar PMIs for several countries around the world.
The index is based on responses from purchasing executives at industrial companies in Canada.
"Despite having dipped to a four-month low in December, the RBC PMI continued to suggest that the manufacturing sector has moved past the weakness at the start of the year," said Cheryl Paradowski, SCMA's president and chief executive officer.
"Importantly, new orders continued to rise strongly, suggesting that overall growth will be sustained moving into 2014."
However, Paradowski added that the employment component of the composite index was disappointing, showing the weakest increase since April.