This study aimed at investigating the process of acquisition of water. surface representation. Children were shown the test papers (a), (b) and (c) on which were drawn the boftles tilted at the angle of 0, 22.5, 45, 67.5, 90, 112.5, 135, 157.5 and 180, and were asked to draw the water surface in these bottles. In test (a) 9 round bottles were drawn on the horizontal table, in test (b) 9 square bdttles on the horizontal table and in test (c) 9 square bottles on the 22.5 tilted stand. Ss were 413 children in every other grade from Ist in elementary school through 9th in junior high school. Ss were classified into 5 stages according to the quality of their drawings. Stage I (12 Ss) : Water stirface is drawn paral-lel to the bottom of bottle in test (b). Stage H (77 Ss) : Water surface in the bottles is drawn obliquely in test (a) and (b).