An evaluation of the radiation dose exposed to the patients in diagnosis is one of most important processes from a viewpoint of radiation protection, but its procedure in general is very complicated because a lot of conversion coefficients are required and these depend on diagnostic conditions. A computer program are newly developed in this report for calculating the patient dose and several parameters such as ESD (entrance surface dose) in plain film radiography, AGD (average glandular dose) in the breast, CTDI (computed tomography dose index), CTDIw (weighted CTDI) and DLP (dose length product) for X-ray CT examination. This program can also cope with different conditions in radiodiagnosis as well as the case without experimental data.