To provide a diagnostic table on which a subject sits and a medical doctor observes anus and rectum disease, and which is easy for an aged person, a handicapped person and a foreigner to use and enables to diagnose with high reliability in visual diagnosis and palpation through anus of lesion exposed by pressurizing abdomen.

In a lateral seat 2 fixed upon leg parts 1 placed on the floor F, a buttocks falling defect 3 for a subject is opened between the observation side rim 2a and the leg/foot side rim 2b of the subject seated toward the arrow mark A. On the back leg side 1c of the leg parts 1, an inserting vacant space 5 for diagnosis is opened which allows to insert a reflective mirror 4 for diagnosis from the backside toward the lower side of the lateral seat 2, the mirror 4 enabling to observe an affected area image of the subject about the exposed affected area in a downward proctoptosis state from the buttocks falling defect 3. This makes diagnostic action of a medical doctor a free without shielding the sight, facilitating visual diagnosis and palpation with a finger.