Synthetic resin container having improved shape stability

The synthetic resin container according to the present invention has a waist dividing a container main body portion into upper and lower parts, wherein the waist is formed on an annular groove surrounding the main body portion to as to be convex toward the interior of the container. The annular groove has reinforcing ribs with a level higher than a groove bottom of the annular groove and lower than the surface of the main body portion. The container main body portion includes reinforcing lateral ribs each having a concave portion which is positioned at the same level as a surface of the container, which or forms a slight step relative to the surface of the container. The main body portion has a plurality of ridges converging toward the associated central convergent point, respectively, thereby defining multi-faceted concave walls inclined toward the associated convergent points, respectively.