Lithium-ion batteries, a type of rechargeable battery, are widely used in home electrical appliances and other products, which are indispensable in our daily lives. However, lithium-ion batteries built into products are often brought to scrap factories without being removed. Lithium-ion batteries can ignite during storage and processing in waste factories. Fires caused by lithium-ion batteries in waste products have actually occurred in waste factories, posing a social problem. Therefore, it is necessary to detect whether or not lithium-ion batteries are included in waste products and to extract them, if any. However, it is difficult to find only the waste products that contain lithium-ion batteries among the huge number of waste products. In this study, we are developing a method to detect only the magnetic signals originating from lithium-ion batteries by applying a magnetic field to batteries. By realizing this method, it will be possible to quickly find lithium-ion batteries in waste products in a non-destructive and non-contact manner, which will help to improve safety and reduce labor in waste factories, and to increase the recycling rate of batteries.