PURPOSE: To enable sure reading without complicating the structure of a reading apparatus, by specifying the direction of each bar of a bar code and a display region.

CONSTITUTION: Each bar of a bar code 12 is directed to the circumferential direction of a specimen test tube 10 and the bar code 12 is displayed so that each bar almost goes round the test tube 10 and the bar arranging direction is directed to the pipe axis direction of the test tube 10. The bar code 12 may be directly recorded or printed on the test tube 10 but it is simple to stick on a preliminarily printed label.