In an image forming apparatus, a controller includes a memory stores control parameters for use in adjustment to be made in at least one of a print density and a color alignment in accordance with a surrounding condition, a print-mode execution module executes a print-mode process of causing the image forming unit to perform image formation, and an adjustive test-mode execution module executes an adjustive test-mode process of causing the image forming unit to perform a test print, thereby determining a control parameter. The print-mode execution module retrieves a relevant control parameter corresponding to a current surrounding condition from the memory, if available, while it causes the adjustive test-mode execution module to execute the adjustive test-mode process, thereby determining a relevant control parameter if the relevant control parameter is not stored in the memory. The retrieved or determined relevant control parameter is applied to the image formation.