The present invention provides a portable casing for carrying instrument, particularly musical instrument, very securely. The casing interior is provided with flexible shock absorbing support(s) on which the non-vulnerable portions of the instrument are laid whereas the delicate and vulnerable portions are held suspended in mid-air. As soon as the casing is closed, the supports get deformed acquiring a loop-shaped structure to encircle and cradle the instrument-parts which overlie thereon and in doing so the instrument is rendered securely captive against any movement In case of accidental impact the stress generated is borne by the soft lining of the casing and by the shock absorbing supports, rendering the instrument unharmed. The shock absorbing supports are advantageously detachably secured to the inner walls of the casing by retaining means. The present invention also provides a method for housing instrument in a portable casing for transportation.