A reflection type magnetooptic sensor head includes a reflection film, a (111) bismuth-substituted iron garnet single crystal film, a polarizer, and a light-inputting/outputting device having an incoming-light path and an outgoing-light path. These structural elements are aligned in this order beginning from a tip end of the magnetooptic sensor head. The two light paths are aligned such that they make an angle substantially greater than five degrees with each other. The reflection type magnetooptic sensor head is used for a magnetooptic measuring apparatus. <IMAGE>
