Left click button does work inappropriately,

Disassemble it and resolder the left mouse micro switch. There's a many different suppliers, but average micro standard is universal. You can replace this with soldering iron or station.

@hyundongsung check your mouse and see if this is a mechanical or electrical issue. Use something like this teardown Logitech Lift Teardown to work on it. Check the plastic parts, the ribbon cable as well as the switch board. Let us know if you find anything that looks odd. Sometimes the top of the switches get wore down and the button does not reach deep enough to activate the switch. Adding a small piece of felt to the top of a switch can restore that function. If not, simply check the switches for function with a multimeter and see if they close the circuit when activated.