An image forming device includes a main body, a replaceable unit, a determination unit, a first memory, a second memory, a temporary memory, a first control unit, and a second control unit. The determination unit determines whether the replaceable unit is a genuine product or a non-genuine product with respect to the main body. The first memory is configured to store a physical value increasing with a use of the main body mounted with the genuine product. The second memory is configured to store the physical value increasing with the use of the main body mounted with the non-genuine product. The temporary memory is configured to temporarily store the physical value increasing with the use of the main body mounted with the non-genuine product.