An image forming apparatus comprising: an image forming portion (Pa, Pb, Pc, Pd, 11, 20) configured to form a toner image on a recording material to execute a job; a fixing portion configured to fix, on the recording material, the toner image formed by said image forming portion (Pa, Pb, Pc, Pd, 11, 20); a mounting portion configured to mount one of a plurality of fixing portions (9, 9A) including a first fixing portion capable of fixing the toner image on the recording material of a predetermined species not including a predetermined recording material and a second fixing portion capable of fixing the toner image on the recording material of a predetermined species including the predetermined recording material; characterized by further comprising: a selecting portion configured to cause an operator to select one of a plurality of modes, the plurality of modes including a first mode in which execution order of a plurality of jobs reserved is changed so as to decrease a number of times of replacement of said fixing portion mounted on said mounting portion and then the plurality of jobs are executed in the changed execution order and a second mode in which the plurality of jobs reserved are executed in reserved order; and a controller configured to control the execution order of the plurality of jobs reserved, according to the mode selected by said selecting portion, wherein in a case that the first mode is selected before the plurality of jobs including a first job using said first fixing portion, a second job using said second fixing portion, a third job using said first fixing portion and a fourth job using said second fixing portion are reserved in this order during execution of a job using said first fixing portion, said controller changes the execution order of the first job, the second job, the third job and the fourth job to an order of the jobs such that both the first job and the third job precede both the second job and the fourth job,, and in a case that the second mode is selected before the plurality of jobs are reserved, when the first job, the second job, the third job and the fourth job are reserved in this order, said controller does not change the execution order. an image forming portion (Pa, Pb, Pc, Pd, 11, 20) configured to form a toner image on a recording material to execute a job; a fixing portion configured to fix, on the recording material, the toner image formed by said image forming portion (Pa, Pb, Pc, Pd, 11, 20); a mounting portion configured to mount one of a plurality of fixing portions (9, 9A) including a first fixing portion capable of fixing the toner image on the recording material of a predetermined species not including a predetermined recording material and a second fixing portion capable of fixing the toner image on the recording material of a predetermined species including the predetermined recording material; characterized by further comprising: a selecting portion configured to cause an operator to select one of a plurality of modes, the plurality of modes including a first mode in which execution order of a plurality of jobs reserved is changed so as to decrease a number of times of replacement of said fixing portion mounted on said mounting portion and then the plurality of jobs are executed in the changed execution order and a second mode in which the plurality of jobs reserved are executed in reserved order; and a controller configured to control the execution order of the plurality of jobs reserved, according to the mode selected by said selecting portion, wherein in a case that the first mode is selected before the plurality of jobs including a first job using said first fixing portion, a second job using said second fixing portion, a third job using said first fixing portion and a fourth job using said second fixing portion are reserved in this order during execution of a job using said first fixing portion, said controller changes the execution order of the first job, the second job, the third job and the fourth job to an order of the jobs such that both the first job and the third job precede both the second job and the fourth job,, and in a case that the second mode is selected before the plurality of jobs are reserved, when the first job, the second job, the third job and the fourth job are reserved in this order, said controller does not change the execution order.