A medical apparatus in which the measurement of an electrocardiogram and the detection of blood leakage that may occur if an accessing unit comes off the patient can be performed accurately without fail, and with which the efficiency in the operation to be performed before the treatment can be improved. A medical apparatus includes a blood purification device including an accessing unit formed of a venous puncture needle stickable into a patient, electrocardiogram-measuring devices closely attached to a skin of the patient and being capable of measuring an electrocardiogram of the patient, and a blood-leakage-detecting device attached to a position near the accessing unit and being capable of detecting blood of the patient that may leak from the accessing unit. The medical apparatus further includes an integrated detecting device provided as a unit including the electrocardiogram-measuring device and the blood-leakage-detecting device.