Statistics Canada says retail sales fell 1.2% to $50.9 billion in October as sales at motor vehicle and parts dealers as well as building material and garden equipment and supplies dealers declined.
Economists on average had expected an increase of 0.5% for the month, according to financial markets data firm Refinitiv.
Statistics Canada says sales fell in eight of 11 subsectors, representing 81% of retail trade.
Sales in the motor vehicle and parts dealers subsector fell 3.2% as sales at new car dealers declined 3.0% and used car dealers dropped 5.2%, the largest decrease since September 2017. Building material and garden equipment and supplies dealers saw sales fall 3.1%.
Sales at gasoline stations rose 1.5% in October, due to higher prices at the pump.
Retail sales in volume terms fell 1.4%.