This work is concerned with a plan for preventing accidents of CO gas leak from gas boilers, involving the enforcement of installations of both CO alarm system and condensing boilers, and financial support of government grants. If amongst 1,460,000 beneficiaries of basic livelihood security, one million households in use of gas boilers receive 3-year support of 200,000 won, the difference of prices between common and condensing boilers, the government grants would be 2,000 billion won. If 3 million common householders are in 3-year support of 100,000 won, government grants would be 3,000 billion won. Therefore, 3-year grand total of government grants would be 5,000 billion won. Finance for government grants can be purveyed from energy saving; yearly 2,000 billion won of energy saving by enforcing to replace one million existing boilers with condensing boilers, leading to 2 trillion won of energy saving for 10 years. In this way, 6,000 billion won of 3-year grand total of government grants for CO alarm system and condensing boilers can be purveyed. The rest amount would be fundraised for energy savings. We claim that our proposal can make an achievement of more than 50% reduction of CO leak accidents during 10 years.