When a holomorphic modular form is a newform, its L-function has nice analytic properties and associates a cuspidal automorphic representation, which is a restricted product of local representations. To recover the newform from the representation, Casselman considered the fixed line of the congruence subgroups of GL(2) at the conductor level on the local representations. A vector on this line shall encode the conductor, the L-function and the \epsilon-factor of the representation. This is called the theory of newforms for GL(2). Similar theory has been established for some groups of small ranks as well as GL(n). In this talk I will introduce one for SO(2n+1).