PURPOSE: To obtain a device for setting molding conditions realizing a higher quality of a molded article.

CONSTITUTION: When an operator conducts a horsepower setting and a pressure setting in a setting device 31, a calculator 32 automatically operates a.speed setting. In this case, a horsepower setting is kept constant, a high speed setting is applied to a low pressure setting, and a speed setting is decreased with increasing pressure setting. At every increase of a pressure setting along a constant-horsepower curve, an injection is carried out. Whether a nondefective article is obtained is judged. Until a nondefective article is obtained, a horsepower setting is increased. When a pressure setting is changed, a constant horsepower setting prevents the forward overshoot of a screw caused by an inertia of its own or an operational lag of a variable delivery pump.