継続記録法（永久在庫法／永久棚卸法）

A perpetual inventory system updates inventory records in real time after each purchase or sale using automated systems like cash registers, barcode scanners, and accounting software. The inventory account increases with purchases and decreases with sales, ensuring records always reflect current stock levels. This real-time data helps managers make informed purchasing and sales decisions.

The perpetual system provides tighter inventory control by allowing companies to monitor stock levels continuously, minimizing stockouts or excess inventory. Real-time visibility enables timely replenishment planning and sales forecasting. This level of responsiveness supports better customer satisfaction and operational efficiency compared to systems relying on infrequent counts.

Despite real-time updates, companies perform periodic physical inventory counts to verify actual stock levels and correct discrepancies caused by theft, spoilage, or data entry errors. These regular checks, typically monthly or quarterly, reconcile recorded inventory with actual inventory and maintain audit compliance, ensuring the system remains accurate.

Barcode scanners, point-of-sale (POS) systems, and inventory management software continuously log purchases and sales in a perpetual system. Each transaction instantly updates the inventory ledger, eliminating delays between when a transaction occurs and when records reflect it. This automation keeps recorded inventory aligned with actual activity.

Real-time inventory visibility enables managers to make informed purchasing and sales decisions based on current stock levels. For example, if a retailer starts with 50 units and sells 5, the system immediately reflects 45 units remaining. This immediate insight supports accurate replenishment planning and sales forecasting.

When a sale occurs, the perpetual system automatically decreases the inventory count by the units sold while simultaneously increasing the cash or bank account by the sale amount. For instance, if Best Appliances sells a refrigerator for three thousand dollars, inventory decreases by one unit and the bank account increases by three thousand dollars instantly.

Retailers selling high-turnover items like smartphones or televisions benefit significantly from perpetual systems because real-time tracking prevents stockouts and excess inventory. The system's continuous monitoring ensures products are available when customers want them while minimizing capital tied up in overstock, supporting both sales and profitability.