PURPOSE: To enable a hollow article to be produced by blow molding even if a flowable material, has a low flowability.

CONSTITUTION: A flowable material is extruded to form a parison. The parison is set in molds 3, 3'. In the first-stage blow molding, the parison is brought into contact with the inner surfaces of the molds 3, 3' at a relatively low blow pressure (a figure (a)). Next, in the second-stage blow molding, the parison is further strongly pressed against the inner surfaces of the molds 3, 3' at a relatively high blow pressure (a figure (b)). This method is useful for producing a hollow article made of ceramic or sintered medal.