The present invention relates to an endoscope insertion portion using an actuator unit and a heater unit together for an imaging unit wherein a shape memory member is used in the actuator unit in order to drive a movable optical member of the imaging unit, which is configured to deform according to the temperature and a heating member is used in the heater unit, which is configured to heat a distal end optical member of the imaging unit.An object of the present invention is to provide an endoscope insertion portion wherein an actuator unit can operate suitably.An endoscope insertion portion is characterized in that the endoscope insertion portion extends in an axial direction and includes: an imaging unit (38) configured to acquire an observation image and including a distal end optical member (44) arranged at a distal end portion of the imaging unit (38), a movable optical member (51) configured to move relative to the distal end optical member (44) and having an optical axis (O) an actuator unit (56) configured to drive the movable optical member (51) and including a shape memory member (58) configured to deform according to temperature and a heater unit (62) including a heating member (63) configured to heat the distal end optical member (44) wherein the heater unit (62) is arranged on a side opposite to a side on which the actuator unit (56) is arranged relative to the optical axis (O) of the imaging unit (38) when viewing in the axial direction of the insertion portion (21).
