20 instead of switching the apparatus on the searching operation can be carried out only when necessary thus the time that is required by the searching operation with the power on can be saved in connection with the first embodiment the cube cassettes 11 110 and 120 have been described as components that constitute an optical element change over control apparatus however searching operation for the number of change over stages of the optical element can be also carried out with respect to replaceable transmissive filter turrets 4 and 40 revolvers 10 and 100 and incident filter turrets 16 and 160 shown in fig1 a second embodiment of the invention will now be described with reference to the flowchart of fig8 an optical element change over control apparatus and an optical microscope using the same according to the second embodiment resemble the ones according to the first embodiment according to the second embodiment switches 100 a and 100 b are additionally used as setting members for previously setting the control section 19 or the operating section 20 to settle whether or not to execute operation for detecting the point of origin of the optical element change over member for example dip switches are used as the switches 100 i a l and 100 b the present invention will now be described in connection with the cube cassette 11 shown in fig3 with reference to the flowchart of fig8 first the state of the switch 100 a or 100 b that is attached to the control section 19 or the operating section 20 is examined step s 1 if the switch 100 a or.