OSAKA, Japan—Panasonic Corp. is introducing convenience-store checkout machines that can scan and bag items on their own, joining Amazon.com Inc. in the push for more retail automation.

In the Panasonic system, demonstrated here Monday, a special shopping basket is designed to detect the merchandise in the basket and calculate the bill. After a customer places the basket in a slot, the bottom of the basket slides out and the merchandise drops into a plastic bag underneath, ready to be carried away. Customers can pay with cash...