Plasticizing Device, Injection Molding Device, And Three-Dimensional Shaping Device

A plasticizing device comprising:

• a motor;
• a screw that has a groove formation surface in which a spiral groove is formed and is rotated about a rotation axis by the motor;
• a barrel that has a facing surface facing the groove formation surface in a direction along the rotation axis and is formed with a communication hole into which a plasticized material obtained by plasticizing a material flows;
• a heater configured to heat the material supplied between the groove formation surface and the facing surface;
• and
• a screw case that is formed with a recessed portion, accommodates the screw in the recessed portion, and is formed with a supply port for supplying the material to the groove, wherein
• a length of the screw in the direction along the rotation axis is smaller than a length in a direction perpendicular to the rotation axis,
• an introduction port that is continuous with the groove is formed in a part of a side surface of the screw that intersects the groove formation surface,
• a length of the introduction port is larger than a length of the supply port in the direction along the rotation axis, and
• a distance between the side surface and an inner wall of the recessed portion varies in a rotation direction of the screw when viewed from the direction along the rotation axis.