Provided is a CZT semiconductor activity meter and an activity measuring device, which relate to the field of medical apparatus and instruments. The CZT semiconductor activity meter includes a shell, a CZT probe, a package substrate and a processing module, wherein the CZT probe is arranged on an end of the shell, the package substrate is arranged at the middle part of the shell and abuts against an inner wall of the shell, the CZT probe is connected to one side of the package substrate, the other side of the package substrate and the inner wall of the shell together form a package inner cavity, and the processing module is accommodated in the package inner cavity and connected to the package substrate. The CZT semiconductor activity meter has a small volume, is convenient to operate, does not require manual control during detection, and can be used at room temperature.