A center wheel module with four axles for a computer mouse comprising: a coder assembly for outputting an encoded pulse electronic signal, a center wheel, and a mouse circuit board, wherein the coder assembly is located around a center shaft of the center wheel, a swing component is installed in a slot on a mouse motherboard or on the mouse circuit board, a front end supporting shaft of the swing component is installed on a front support of the mouse motherboard or of the mouse circuit board, grooves (32, 33) are set at both sides of the swing component to support the center wheel, first touch arms (36, 37) for cooperating with switches (5, 6) on the mouse circuit board are set at the left and right sides of the swing component, a further touch arm, of a wheel downward press key, is set at a trailing end of the swing component, and a wheel downward press key switch is set on the mouse circuit board below the further touch arm a position limiting device is set respectively on the swing component and on the mouse circuit board, for preventing generation of left or right misoperation signals by left or right swinging of the swing component during a downward press operation, wherein one of the front supporting shaft or a back supporting shaft (34, 341) installed on a back support is configured to have a sector-shaped section, the corresponding front or back support (71, 72) being configured to have a sector-shaped groove that clips the sector-shaped section, and the bottom of the supporting shaft (34, 341) having the sector-shaped section is an arc surface, a plane or an acute angle, the bottom of the sector-shaped groove of the corresponding front or back support (71, 72) being a corresponding arc surface, plane or acute angle. a coder assembly for outputting an encoded pulse electronic signal, a center wheel, and a mouse circuit board, wherein the coder assembly is located around a center shaft of the center wheel, a swing component is installed in a slot on a mouse motherboard or on the mouse circuit board, a front end supporting shaft of the swing component is installed on a front support of the mouse motherboard or of the mouse circuit board, grooves (32, 33) are set at both sides of the swing component to support the center wheel, first touch arms (36, 37) for cooperating with switches (5, 6) on the mouse circuit board are set at the left and right sides of the swing component, a further touch arm, of a wheel downward press key, is set at a trailing end of the swing component, and a wheel downward press key switch is set on the mouse circuit board below the further touch arm a position limiting device is set respectively on the swing component and on the mouse circuit board, for preventing generation of left or right misoperation signals by left or right swinging of the swing component during a downward press operation, wherein one of the front supporting shaft or a back supporting shaft (34, 341) installed on a back support is configured to have a sector-shaped section, the corresponding front or back support (71, 72) being configured to have a sector-shaped groove that clips the sector-shaped section, and the bottom of the supporting shaft (34, 341) having the sector-shaped section is an arc surface, a plane or an acute angle, the bottom of the sector-shaped groove of the corresponding front or back support (71, 72) being a corresponding arc surface, plane or acute angle.