An image forming apparatus comprising: accepting means (36, 37) for accepting a printing job including image data; image forming means for forming an image based on the printing job accepted by the accepting means (36, 37); a mark sensor for detecting a mark formed by using the image forming means; control means for controlling the accepting means (36, 37) and the image forming means and processing the printing job accepted by the accepting means (36, 37); determining means for determining, when the accepting means (36, 37) accepts a printing job, whether the accepted printing job is a first printing job corresponding to a predetermined attribute or a second printing job not corresponding to the predetermined attribute; and standby means for placing, when the determining means determines that the printing job accepted by the accepting means (36, 37) is the first printing job, the first printing job in a standby state, wherein the control means is configured to start a process of the second printing job, and to execute an obtaining process for obtaining information for adjusting an image formation result, when the determining means determines that the printing job accepted by the accepting means (36, 37) is the second printing job, and wherein the control means is configured to form and detect a mark to be used for adjusting the image formation result by using the image forming means and to detect the mark by using the mark sensor; and to obtain a correction value to be used for adjusting the image formation result based on a detection result of the formed mark, as the obtaining process, characterized in that the obtaining process for obtaining information for adjusting an image formation result is executed by using start of the process of the second printing job as a trigger; the determining means is configured to determine whether or not standby time of the first printing job placed in a standby state by the standby means is not less than predetermined time; and the control means is configured to start a process of the first printing job placed in a standby state, under condition of execution of the obtaining process triggered by the start of the process of the second printing job or when the determining means determines that the standby time of the first printing job placed in a standby state by the standby means is not less than the predetermined time and further comprising memory means for storing a printing job and the determining means is configured to determine whether or not a free space of the memory means is smaller than a predetermined threshold value, and wherein the control means is configured to process the first printing job without placing in a standby state when the determining means determines that the free space of the memory means is smaller than the predetermined threshold value. accepting means (36, 37) for accepting a printing job including image data; image forming means for forming an image based on the printing job accepted by the accepting means (36, 37); a mark sensor for detecting a mark formed by using the image forming means; control means for controlling the accepting means (36, 37) and the image forming means and processing the printing job accepted by the accepting means (36, 37); determining means for determining, when the accepting means (36, 37) accepts a printing job, whether the accepted printing job is a first printing job corresponding to a predetermined attribute or a second printing job not corresponding to the predetermined attribute; and standby means for placing, when the determining means determines that the printing job accepted by the accepting means (36, 37) is the first printing job, the first printing job in a standby state, wherein the control means is configured to start a process of the second printing job, and to execute an obtaining process for obtaining information for adjusting an image formation result, when the determining means determines that the printing job accepted by the accepting means (36, 37) is the second printing job, and wherein the control means is configured to form and detect a mark to be used for adjusting the image formation result by using the image forming means and to detect the mark by using the mark sensor; and to obtain a correction value to be used for adjusting the image formation result based on a detection result of the formed mark, as the obtaining process, characterized in that the obtaining process for obtaining information for adjusting an image formation result is executed by using start of the process of the second printing job as a trigger; the determining means is configured to determine whether or not standby time of the first printing job placed in a standby state by the standby means is not less than predetermined time; and the control means is configured to start a process of the first printing job placed in a standby state, under condition of execution of the obtaining process triggered by the start of the process of the second printing job or when the determining means determines that the standby time of the first printing job placed in a standby state by the standby means is not less than the predetermined time and further comprising memory means for storing a printing job and the determining means is configured to determine whether or not a free space of the memory means is smaller than a predetermined threshold value, and wherein the control means is configured to process the first printing job without placing in a standby state when the determining means determines that the free space of the memory means is smaller than the predetermined threshold value.