Image pickup apparatus, electronic endoscope, and lens unit

An electronic endoscope comprising:

• an insertion portion that is inserted into a subject/object to be examined and
• an image pickup apparatus that varies optical properties by moving a part of lenses of an objective lens that is contained in the insertion portion and that observes inside the subject/object to be examined by means of the image pickup apparatus, wherein the image pickup apparatus comprises:
• a solid-state image pickup device unit that is arranged at a rear-end section and that subjects a subject image to photoelectric conversion;
• a fixed lens frame that retains the objective lens that is disposed to the front of the solid-state image pickup device unit;
• a movable lens frame that retains the part of lenses that moves along a photographing optical axis inside the fixed lens frame;
• and
• an actuator that moves the movable lens frame forward and backward, the actuator including:
• a rod-shaped rigid member that has one end connected to the movable lens frame;
• a shape memory alloy that is coupled to the rod-shaped rigid member;
• a guide pipe into which the rod-shaped rigid member is insertedly fitted in a condition in which the rod-shaped rigid member can move forward and backward, the guide pipe being fixed to the fixed lens frame and rectilinearly guiding the rod-shaped rigid member in a photographing optical axis direction of the solid-state image pickup device unit;
• and
• a fixing member that fixes an axial position of the guide pipe in the fixed lens frame in a condition in which the axial position of the guide pipe can be varied within a clearance in a circumferential direction of the guide pipe, the clearance being formed between the guide pipe and the fixed lens frame.