PROBLEM TO BE SOLVED: To provide an endoscope observation support device which effectively supports observation with an ultrasonic probe.SOLUTION: An endoscope observation support device includes: an ultrasonic probe 32 which can change a projection amount from an endoscope tip part a sensor device 18 which detects the tip positions of an endoscope 26 and the ultrasonic probe 32 a camera/ultrasonic image observation position estimation part 56 which performs association between the observation positions of the endoscope 26 and the ultrasonic probe 32 in a three-dimensional image of luminal organs constructed based on three-dimensional image data an ultrasonic image acquisition part 48 which consecutively acquires a plurality of ultrasonic images of the observation positions while changing the projection amount of the ultrasonic probe 32 and an ultrasonic image three-dimensional reconstruction part 72 which reconstructs a three-dimensional image of the observation position by the ultrasonic probe 32 on the basis of the plurality of acquired ultrasonic images, suitably grasps correspondence between the observation position of the ultrasonic probe 32 and the three-dimensional image of luminal organs and reconstructs a three-dimensional image of a target site.
