An injection valve of the high pressure homogenizer includes: a fixed member having a material introducing passage therein; and a movable member disposed rotatably, swingably, or pulsatingly opposite to the fixed member in an axial direction of the fixed member, wherein the orifice of the injection valve is made of a fine gap in a radial direction disposed between an end face of the fixed member facing an end of the material introducing passage and an end face of the movable member disposed at an end of the movable member opposed to the fixed member. The orifice is communicated with the colliding wall at the circumference of the orifice and the material processing passage on the secondary side. Furthermore, the invention also relates to an injection valve unit of the high pressure homogenizer.