Abstract: A thin-walled can for sealingly enclosing liquid or gas, including a dome section, a counter section, a ground section, a heel section, and a side wall section, is improved so as to enhance pressure-proofness for a given wall thickness or to reduce wall thickness for a given pressure-proofness. A cross sectional shape of the dome section is formed of a curve whose radius of curvature changes substantially continuously along the curve, and the counter section contiguous to the dome section is formed so as to align with the direction of extension of the dome section. Preferably, the angle formed between the cross-section of the counter section and a vertical line is chosen to be within the range of 0.degree. to 15.degree.. Furthermore, preferably the cross-sectional shape of the heel section extending from the counter section through the ground section to the side wall section is a circular arc that is inwardly convex.