603 if the second exposure evaluation value is larger than the second predetermined value it is determined that the current focal point evaluation value is generated from an image signal with a sufficient s n ratio and the control signal of the focus lens 103 is generated using the second focal point evaluation value step s 602 followed by terminating the process if the second exposure evaluation value is equal to or smaller than the second predetermined value no to the step s 603 then it is determined that the focal point evaluation value is generated from a low s n image signal the generation of the focus lens control signal from the focal point evaluation value is stopped and the previous focus lens control is kept step s 604 followed by terminating the process during the sampling cycle 504 for a focal point evaluation value in fig5 an up arrow indicates the case where the microcomputer 113 generates the control signal of the focus lens using a focal point evaluation value calculated by the focal point evaluation value calculation circuit 118 while a right arrow indicates the case where there is no use of the focal point evaluation value according to the present embodiment the exposure evaluation value second exposure evaluation value of the image signal synthesized by the image synthesis circuit 108 is calculated and a focal point evaluation value decided to have a favorable s n ratio is used to control the focus lens 103 this can increase the number of times of sampling the focal point evaluation values thereby restraining a decrease in autofocus responsiveness by fast.