Giant Food Inc. has sold its Pants Corral group of casual-clothing stores to Carson Pirie Scott & Co. of Chicago, officials of the Landover-based supermarket chain said yesterday.

Although neither company would disclose the price, a Giant official acknowledged that it has agreed to sell 20 of the 28 Pants Corral stores for an amount "in excess of $2 million." An exact figure will be disclosed when the transaction is completed on June 1, the official said.

The remaining eight Pants Corral stores will be converted to other uses, said David B. Sykes, Giant's secretary and senior vice president for finance. "We will not be in the Pants Corral business much after June 1," Sykes said, adding that Giant already has begun an inventory-reduction sale at the clothing chain. Sykes said the 150 or so Pants Corral employes will be absorbed by Giant's supermarkets and other divisions.

According to Sykes, Giant had been seeking a buyer for Pants Corral for several months, even though it had been profitable. He said Giant decided to get out of the retail clothing business because "this really wasn't our cup of tea. We know the food and drug business."

Giant operates 132 supermarkets -- 74 of them food-pharmacy combinations -- in the Washington and Baltimore markets, where it is the leading food retailer. It reported sales of $2.1 billion for the fiscal year ended in February. The Pants Corral division contributed annual sales of between $15 million and $20 million to Giant's total volume, not a very significant amount, according to Sykes.

Giant spun off the Pants Corral chain about 20 years ago from its department stores, which were closed in 1978. The clothing group, which is a major outlet in the Washington area for Levi jeans and other casual wear, operated as many as 33 stores.

Carson Pirie officials could not be reached yesterday, but Sykes said the Chicago company had been trying for some time to extend its retail operations to the Washington market. The purchase of the Pants Corral chain "gives them ready-made locations and makes the transaction very desirable for them and for us," Sykes said.

Carson Pirie has three basic lines of business. Its retail group consists of the Carsons department stores, primarily in Illinois, and a chain of specialty casual wear stores. The food service and lodging group consists of the Dobbs House Inc. and Toddle House restaurant chains; Ridgewell Caterers Inc. of Bethesda; an airline catering and concessions service, and conference-center hotels. Carson Pirie also operates a wholesale floor-covering distribution division.

Carson Pirie reported sales of $798 million in 1983.