[Problem] To provide a guidewire that has good operability and that can perform procedures efficiently.[Solution to Problem] A guidewire is for guiding insertion of a medical appliance into a subject. The guidewire includes an inserting portion and an observation optical system. The inserting portion has a first part and a second part that has higher flexibility than the first part, and the inserting portion is to be inserted into the subject. The observation optical system is provided to the inserting portion, and the observation optical system is provided for observing inside the subject.
