Kim B. Bruce gave a system of axioms lor second order logic
L(
Q). H. J. Keisler presented a system of axioms for infinilary logic. This article gives a system of axioms and model theory for infinitary second order logic
LW1W(
Q), based on the combination of both ideas of the systems and application of the consistency property; proves the model existence theorem and completeness theorem in L
w1w(
Q).