An image pick-up apparatus comprising: image shooting means for shooting a subject to generate an input image signal having an image shooting frame rate; addition processing means for performing frame addition on the input image signal to generate an output image signal having an output frame rate, wherein said frame addition comprises adding together a plurality of frames of said input image signal; and control means for controlling a variation of the image shooting frame rate in the image shooting means and/or a switch of number of additive frames in the frame addition in the addition processing means, in accordance with output frame rate set state, to set the output image signal as the one having a frame rate based on the output frame rate set state; the addition processing means comprising: a plurality of memory elements (414-1, 414-2, 414-3) with an associated input selector (412, 413) and an associated output selector (415, 416) to enable individual memory elements in the plurality to be selected for input and for output; an adder arranged to generate a sum frame by adding a frame of the input image signal to a frame stored in one of the memory elements selected by the output selector under control of the control means; the input selector arranged, under control of the control means, to select one of the memory elements and to store in that selected memory element either the sum frame or a frame of the input image signal; and the output selector further being arranged, under the control of the control means, to provide said output image signal. image shooting means for shooting a subject to generate an input image signal having an image shooting frame rate; addition processing means for performing frame addition on the input image signal to generate an output image signal having an output frame rate, wherein said frame addition comprises adding together a plurality of frames of said input image signal; and control means for controlling a variation of the image shooting frame rate in the image shooting means and/or a switch of number of additive frames in the frame addition in the addition processing means, in accordance with output frame rate set state, to set the output image signal as the one having a frame rate based on the output frame rate set state; the addition processing means comprising: a plurality of memory elements (414-1, 414-2, 414-3) with an associated input selector (412, 413) and an associated output selector (415, 416) to enable individual memory elements in the plurality to be selected for input and for output; an adder arranged to generate a sum frame by adding a frame of the input image signal to a frame stored in one of the memory elements selected by the output selector under control of the control means; the input selector arranged, under control of the control means, to select one of the memory elements and to store in that selected memory element either the sum frame or a frame of the input image signal; and the output selector further being arranged, under the control of the control means, to provide said output image signal. a plurality of memory elements (414-1, 414-2, 414-3) with an associated input selector (412, 413) and an associated output selector (415, 416) to enable individual memory elements in the plurality to be selected for input and for output; an adder arranged to generate a sum frame by adding a frame of the input image signal to a frame stored in one of the memory elements selected by the output selector under control of the control means; the input selector arranged, under control of the control means, to select one of the memory elements and to store in that selected memory element either the sum frame or a frame of the input image signal; and the output selector further being arranged, under the control of the control means, to provide said output image signal.