All the colours have different meanings as follows.
The red represents the blood of the people who sacrificed their life to fight for freedom from all foreign invasion and control.
The Blue represents the abundance of the country with its natural resources like forests, rivers, mines and fertile land.
The white circle represents the full moon rising at the month of "Deune khun". According to the Buddhist calendar, during this time of the month, people celebrate and enjoy the rising of the full moon, for they can see things as clear as daylight. This white circle also represents a good sign of peace, unity and future prosperity of the country.