A hemodialysis apparatus and method capable of performing an optimal ultrafiltration is provided to calculate a standardized parameter applicable to a large number of patients relating a predetermined blood benchmark to a body weight of a patient during a hemodialysis treatment in correlation with a dry-weight of the patient. There are provided a dialysis treatment means (ultrafiltration pump 8) for performing hemodialysis and ultrafiltration upon an extracorporeally-circulating blood of the patient to conduct a hemodialysis treatment, a measuring means 10 for measuring a variation rate of the body weight of the patient during the hemodialysis treatment by using the dialysis treatment means and a variation rate of a volume of an extracorporeally-circulating blood plasma obtained by a hematocrit sensor 5, and a calculation means 11 for calculating a parameter (PWI) relating the variation rate of the body weight obtained by the measuring means 10 to the variation rate ofthe extracorporeally-circulating blood plasma in correlation with the dry-weight of the patient.本發明的課題在於提供一種血液透析裝置和血液透析方法,其將透析治療中之患者的規定的血液指標和體重賦予關聯,並且算出與患者的乾重相關,適用於許多患者的標準化的參數,可進行適合的除水。具備:透析處理手段(除水泵(8)),該透析處理手段對進行體外循環之患者的血液進行血液透析處理和除水,以進行透析治療;測定手段(10),該測定手段(10)測定採用上述透析處理手段的透析治療中之患者的體重變化率、通過血球比容感測器(5)獲得的循環血漿量變化率;及算出手段(11),該算出手段在透析治療中算出與患者的乾重相關、並且使通過測定手段(10)獲得的使體重變化率和循環血漿量變化率賦予關聯的參數(PWI)。
