The present invention relates to a mouse for a computer, which is a computer input device. The mouse has an upper case with a vertical cushioning function against force imposed on the mouse, and thus can operate smoothly. The present invention provides a cushioning function to a mouse, thereby eliminating fatigue and muscle pain of the wrist and fingers even when a user uses the mouse for a long time. The mouse is manufactured by assembling an upper case and a lower case, and is configured such that a protrusion box which protrudes upwards is formed on the lower case, a boss is fixed on the lower side of the upper case and penetrates the protrusion box, thereby being joined with the same, and a spring which is supported by the protrusion box is inserted into the boss from the outside while the lower side of the boss can be prevented from being separated from the protrusion box.