We define the categories of log motives and log mixed motives. The latter gives a new
formulation for the category of mixed motives. We prove that the former is a
semisimple abelian category if and only if the numerical equivalence and homological
equivalence coincide, and that it is also equivalent to the latter being a Tannakian
category. We discuss various realizations, formulate Tate and Hodge conjectures, and
verify them in the curve case.