An intra-subject information acquiring system comprising: a body-insertable apparatus insertable into a subject, and being configured to transmit acquired image information to a receiver outside of the subject as a radio signal; a receiving apparatus comprising: - a reference clock configured to output a clock signal that becomes a processing reference to the radio signal; - a detector configured to detect a detection pulse signal (Hd) of a horizontal synchronization signal from an image signal of one frame having a plurality of line information components and the horizontal synchronization signal attached to each line information component; - an image processor configured to perform an image generation process of each frame based on the horizontal synchronization signal detected by the detector; - a storage unit configured to store an image of each frame generated by the image processor; and - an image deletion controller configured to: -- control to delete an image of a current frame, when the image deletion controller determines that there is a time when the detector cannot continuously detect the horizontal synchronization signal by a predetermined number of times or more in one frame based on the detection pulse signal of the horizontal synchronization signal, and -- control to store the image of a current frame into the storage unit when the image deletion controller determines that there is not a time when the detector cannot continuously detect the horizontal synchronization signal by a predetermined number of times or more in one frame based on the detection pulse signal of the horizontal synchronization signal. a body-insertable apparatus insertable into a subject, and being configured to transmit acquired image information to a receiver outside of the subject as a radio signal; a receiving apparatus comprising: - a reference clock configured to output a clock signal that becomes a processing reference to the radio signal; - a detector configured to detect a detection pulse signal (Hd) of a horizontal synchronization signal from an image signal of one frame having a plurality of line information components and the horizontal synchronization signal attached to each line information component; - an image processor configured to perform an image generation process of each frame based on the horizontal synchronization signal detected by the detector; - a storage unit configured to store an image of each frame generated by the image processor; and - an image deletion controller configured to: -- control to delete an image of a current frame, when the image deletion controller determines that there is a time when the detector cannot continuously detect the horizontal synchronization signal by a predetermined number of times or more in one frame based on the detection pulse signal of the horizontal synchronization signal, and -- control to store the image of a current frame into the storage unit when the image deletion controller determines that there is not a time when the detector cannot continuously detect the horizontal synchronization signal by a predetermined number of times or more in one frame based on the detection pulse signal of the horizontal synchronization signal. - a reference clock configured to output a clock signal that becomes a processing reference to the radio signal; - a detector configured to detect a detection pulse signal (Hd) of a horizontal synchronization signal from an image signal of one frame having a plurality of line information components and the horizontal synchronization signal attached to each line information component; - an image processor configured to perform an image generation process of each frame based on the horizontal synchronization signal detected by the detector; - a storage unit configured to store an image of each frame generated by the image processor; and - an image deletion controller configured to: -- control to delete an image of a current frame, when the image deletion controller determines that there is a time when the detector cannot continuously detect the horizontal synchronization signal by a predetermined number of times or more in one frame based on the detection pulse signal of the horizontal synchronization signal, and -- control to store the image of a current frame into the storage unit when the image deletion controller determines that there is not a time when the detector cannot continuously detect the horizontal synchronization signal by a predetermined number of times or more in one frame based on the detection pulse signal of the horizontal synchronization signal. -- control to delete an image of a current frame, when the image deletion controller determines that there is a time when the detector cannot continuously detect the horizontal synchronization signal by a predetermined number of times or more in one frame based on the detection pulse signal of the horizontal synchronization signal, and -- control to store the image of a current frame into the storage unit when the image deletion controller determines that there is not a time when the detector cannot continuously detect the horizontal synchronization signal by a predetermined number of times or more in one frame based on the detection pulse signal of the horizontal synchronization signal.