Disclosed is a set for determining whether blood obtained in puncture tools (14, 220) by puncturing a blood vessel is venous blood or arterial blood easily, and ensuring handling under a sterile state. A set (10a) for determining blood type has a cover body (12a) to be attached to a syringe set (14), and a blood type determination unit (16a) to be housed in the cover body (12a). The blood type determination unit (16a) comprises a light projecting portion (27) and a light receiving element (26), and a blue output LED (28) and a red output LED (30) showing a judgment result based on a signal obtained from the light receiving element (26). The cover body (12a) has a body (60) and a lid (64) that are combined with each other to cover the blood type determination unit (16a), a partition (72) for passing blood between the light projecting portion (27) and the light receiving element (26), and a pair of measurement windows (82, 84) for transmitting light between the light projecting portion (27) and the light receiving element (26) through the partition (72).
