A resin material plasticizing device is equipped with a heating block in which a passage hole is formed to which there is supplied an elongate solid coating material, and which is capable of raising the temperature of an inner wall surface of the passage hole. At an upstream portion of the passage hole, so that an inner wall surface thereof is kept in contact with a side surface of the solid coating material, a cross section thereof which is perpendicular to an axial direction has a shape corresponding to the cross-sectional shape of the solid coating material. At least a part of the midstream portion is set in a manner so that a ratio of a circumferential length with respect to a cross-sectional area of a cross section perpendicular to the axial direction is greater than the same ratio of the upstream portion.