A rigid endoscope set according to the invention includes a rigid endoscope body having a first insertion portion inserted into a subject, a first channel provided in the first insertion portion and an ultrasound observation section disposed at a distal end of the first insertion portion to observe the subject, a treatment instrument guide having a second insertion portion configured to be inserted into or removed from the first channel and a second channel provided in the second insertion portion, and an optical telescope having a needle portion configured to be insertable into or removable from the second channel, a third insertion portion configured to be insertable into or removable from the first channel instead of the treatment instrument guide and an optical observation section disposed at a distal end of the third insertion portion to observe the subject.
