PROBLEM TO BE SOLVED: To provide a medical bed apparatus preventing deterioration in photographing accuracy and mechanical safety and capable of photographing the whole body of a test object with a single device, and a diagnostic device using the same.SOLUTION: A medical bed apparatus 10 includes a support 11 to be disposed at an installation place, and a long top board 13 on which the test object is placed. The medical bed apparatus 10 further includes: an intermediate plate 12 that has a substantially rectangular plate-like shape and is disposed between the support 11 and the top board 13； an intermediate plate slide mechanism 20 that can move the intermediate plate 12 in the longitudinal direction with respect to the support 11； and a top board rotation mechanism 50 that can move the top board 13 about a top board vertical axis with respect to the intermediate plate 12.
