A contact lens (10) comprises the following structure. An optical portion (26) is formed on front and rear surfaces devoid of a biased gravity center resulting from creating a prism. Upper and lower thin portions (42, 44) are formed on upper and lower portions of a periphery portion (31). Thick portions (50) are formed on the right and left of the periphery portion (31). The thick portions (50) each extend to upper and lower sides across a horizontally-extending horizontal radial direction line (15). The thick portion (50) extends for a greater distance to the lower side than to the upper side, thereby biasing downward a location of its gravity center. Upper and lower transition portions (52, 54) the thickness dimensions of which are gradually changed in a circumference direction between the thin portions (42, 44) and the thick portions (50) are formed on the periphery portion (31). An inclination of the lower transition portion (54) is set to be steeper than that of the upper transition portion (52).