Anisocoria after induction of general anesthesia may indicate a severe cerebrovascular disorder. We encountered a case in which anisocoria in the left and right eyes was noticed after induction of general anesthesia, and the surgery was canceled. The patient was a 53-year-old woman with a history of hypertension. She received general anesthesia 10 years ago, but the details were unknown. Anesthesia was induced with propofol, remifentanil, and rocuronium, followed by nasal intubation. No significant change was observed in vital signs during the induction of anesthesia. After intubation, the pupils were checked according to the protocol for observing pupil diameter. The pupil size was found to be unequal, measuring 1 mm in the left eye and 4 mm in the right eye. A cerebrovascular disorder was suspected; thus, the surgery was canceled, and the patient was awakened and extubated. Neurological symptoms such as limb movements were checked after awakening, and no disorientation or motor dysfunction was detected in the patient. However, her pupils remained unequal, measuring 2 mm in the left eye and 4 mm in the right eye. Regarding light reflex, the left eye was miotic, but the right eye remained mydriatic. The pupillary symptom persisted even during discharge the next day. Since our hospital is a solely dental hospital, following discharge, after consulting the ophthalmology department of a nearby medical university hospital, the patient was diagnosed with pupillotonia, as she had been experiencing light dazzling in only her right eye for seven years, had no light reflex but near reflex, and was miotic due to the use of pilocarpine hydrochloride eye drops, which promotes miosis. The patient has had these symptoms in the right eye for seven years, and it is possible that she had anisocoria during the preoperative examination at this time. If anisocoria had been detected and examined carefully during the preoperative examination, there would have been no need to cancel the surgery. In this case, we strongly felt that the pupils must be checked during the preoperative examination.