PURPOSE: To stably obtain a spherical body with high sphericity, by a method wherein a density gradient continuous in vertical direction is set in a specified liquid when a spherically shaped body used as an artificial valve for an artificial heart is shaped by pouring a liquid material to be shaped into the specified liquid and by hardening it during its flotation.

CONSTITUTION: A density gradient continuous in the direction of depth is formed in a liquid 35 in which a solution 28 of material to be shaped is poured when a ball is shaped. This density gradient is linearly changed and needs to be formed in the liquid 35 per se. In this way, the solution 28 poured is allowed to behave so as not to float or sink more than the solution needs, and is allowed to harden while floating and receiving equal force from the whole periphery thereof, at the position where the solution 28 is balanced with the liquid 35, and thus the solution 28 is spherically shaped in the condition that impact is not applied, and the ball with high sphericity can be obtained. As the liquid 35, a single polymer or solution is used, in which protective colloid or a surface- active agent or the like is added, and as the solution 28, a dual-soluble, room temperature setting type monomer or the like is used.