  Effects of non-resonant photoproductions arising from two different $\pi NN$
couplings are investigated in the $\gamma N\to\pi\pi N$ reaction. We find that
the pseudoscalar (PS) $\pi NN$ coupling is generally preferable to the
pseudovector (PV) $\pi NN$ coupling and particularly the total cross sections
are successfully described by the model with the PS $\pi NN$ coupling. In order
to see the difference between the two couplings, we also show the results of
invariant mass spectra and helicity-dependent cross sections in various isospin
channels calculated with the PS and PV couplings.
