A method for determining a blood specimen, the method comprising preparing a first measurement sample by mixing a blood specimen of a subject with a first coagulation time measurement reagent and measuring first coagulation time, preparing a second measurement sample by mixing the blood specimen with a second coagulation time measurement reagent and measuring second coagulation time, preparing a third measurement sample by mixing the blood specimen with a third coagulation time measurement reagent and measuring third coagulation time, preparing a fourth measurement sample by mixing the blood specimen with a fourth coagulation time measurement reagent and measuring fourth coagulation time, acquiring a value based on the first coagulation time and the second coagulation time, and acquiring a value based on the third coagulation time and the fourth coagulation time, wherein the first coagulation time measurement reagent is a coagulation time measurement reagent containing phospholipids, the second coagulation time measurement reagent is a coagulation time measurement reagent containing phospholipids, and a metal ion and/or normal plasma, wherein the metal ion is at least one metal ion selected from a nickel ion, a cobalt ion, a manganese ion, a zinc ion, an aluminum ion, an iron ion, a sodium ion, and a potassium ion, the third coagulation time measurement reagent is a coagulation time measurement reagent containing phospholipids at a concentration higher than that of the first coagulation time measurement reagent, the fourth coagulation time measurement reagent is a coagulation time measurement reagent containing a metal ion and/or normal plasma and also containing phospholipids at a concentration higher than that of the first coagulation time measurement reagent and that of the second coagulation time measurement reagent, wherein the metal ion is at least one metal ion selected from a nickel ion, a cobalt ion, a manganese ion, a zinc ion, an aluminum ion, an iron ion, a sodium ion, and a potassium ion, the first, second, third and fourth coagulation time measurement reagents contain a component necessary for coagulation selected from the group consisting of activators, snake venom and tissue factors, and the values are used to determine whether the blood specimen of a subject is a blood specimen containing a lupus anticoagulant or a blood specimen containing a direct anticoagulant, wherein the value of the index calculated by equation, or below is compared with a threshold value corresponding to the index, and a determination is made based on the comparison result. Index = Second coagulation time / First coagulation time × Fourth coagulation time / Third coagulation time Index = First coagulation time / Second coagulation time × Third coagulation time / Fourth coagulation time or Index = First coagulation time × Second coagulation time × Third coagulation time × Fourth coagulation time preparing a second measurement sample by mixing the blood specimen with a second coagulation time measurement reagent and measuring second coagulation time, preparing a third measurement sample by mixing the blood specimen with a third coagulation time measurement reagent and measuring third coagulation time, preparing a fourth measurement sample by mixing the blood specimen with a fourth coagulation time measurement reagent and measuring fourth coagulation time, acquiring a value based on the first coagulation time and the second coagulation time, and acquiring a value based on the third coagulation time and the fourth coagulation time, wherein the first coagulation time measurement reagent is a coagulation time measurement reagent containing phospholipids, the second coagulation time measurement reagent is a coagulation time measurement reagent containing phospholipids, and a metal ion and/or normal plasma, wherein the metal ion is at least one metal ion selected from a nickel ion, a cobalt ion, a manganese ion, a zinc ion, an aluminum ion, an iron ion, a sodium ion, and a potassium ion, the third coagulation time measurement reagent is a coagulation time measurement reagent containing phospholipids at a concentration higher than that of the first coagulation time measurement reagent, the fourth coagulation time measurement reagent is a coagulation time measurement reagent containing a metal ion and/or normal plasma and also containing phospholipids at a concentration higher than that of the first coagulation time measurement reagent and that of the second coagulation time measurement reagent, wherein the metal ion is at least one metal ion selected from a nickel ion, a cobalt ion, a manganese ion, a zinc ion, an aluminum ion, an iron ion, a sodium ion, and a potassium ion, the first, second, third and fourth coagulation time measurement reagents contain a component necessary for coagulation selected from the group consisting of activators, snake venom and tissue factors, and the values are used to determine whether the blood specimen of a subject is a blood specimen containing a lupus anticoagulant or a blood specimen containing a direct anticoagulant, wherein the value of the index calculated by equation, or below is compared with a threshold value corresponding to the index, and a determination is made based on the comparison result. Index = Second coagulation time / First coagulation time × Fourth coagulation time / Third coagulation time Index = First coagulation time / Second coagulation time × Third coagulation time / Fourth coagulation time or Index = First coagulation time × Second coagulation time × Third coagulation time × Fourth coagulation time