Statistics Canada says total manufacturing sales fell 1% to $71.5 billion in October.
The agency says sales were down in 11 of the 21 subsectors it tracks as sales of chemical products fell 6%.
Meanwhile, sales in the wood product subsector fell 9% as wood product manufacturing in Canada were affected by U.S. tariffs.
Transportation equipment subsector sales dropped 2.3% in October as the production of aerospace product and parts industry group posted the largest decrease at 6.3%.
The motor vehicle industry group, which is also included in the transportation equipment subsector, saw sales fall 2%.
In real terms, Statistics Canada says overall manufacturing sales fell 1.5% in October.