This composite image generation system is provided with: a position information detection device 14 for detecting position information of a predetermined site in an actual space； and a processing device 16 for generating, on the basis of the position information from the position information detection device 14, a composite image in which a superimposition image acquired separately is superimposed on a desired region in a camera image of the actual space captured by a video camera 18 movably disposed. The processing device 16 comprises a position information identification means 35 for adjusting the detection result from the position information detection device 14 and identifying the position information of a probe 19 which is used when the superimposition image is superimposed on the desired region. The position information identification means 35 is provided with: a recognition state determination unit 46 for determining the state of recognition of a probe maker 24A by the video camera 18； a to-be-used information selection unit 47 for selecting either a detection result from an optical tracking means 21 or a detection result from a non-optical tracking means 22 to be used according to the recognition state； and an output position information determination unit 48 for determining output position information necessary for the generation of the composite image on the basis of the position information selected.L'invention concerne un système de génération d'image de synthèse, lequel comporte: un dispositif de détection (14) d'informations de position qui détecte des informations de position d'un emplacement prédéfini à l'intérieur d'un espace réel； et un dispositif de traitement (16) qui, sur la base des informations de position du dispositif de détection (14) d'informations de position, génère dans une région voulue à l'intérieur d'une image d'espace réel capturée à l'aide d'une caméra vidéo (18) disposée de façon à pouvoir se déplacer, une image de synthèse dans l
