PROBLEM TO BE SOLVED: To provide an indicator, an X-ray CT device and a medical information processing device which make it possible to efficiently conduct puncture treatment.SOLUTION: An indicator comprises an indication part and a control mechanism. The indication part indicates the insertion angle of an insertion into a subject. The control mechanism controls the angle of the indication part on the basis of information on the three-dimensional insertion angle of the insertion into the subject.COPYRIGHT: (C)2016,JPO&INPIT