Wiggler radiation contains not only the usual component with short wavelength radiation but also a broadband component in the long wavelength region, which emits in the near forward direction, peaked at an angle 1/γ. Firstly, spontaneous radiation from a wiggler is analyzed based on the basic formula of electrody namics. With the long wavelength approximation, a formula for the long wavelengt h is obtained. The theoretical result is well coincided with the result of numer ical calculation. Also the character of this radiation is analyzed. Secondly, th e photon fluxes coming separately from the wiggler and a bending magnet are comp ared, for the wavelength longer than 1μm. The result shows the superiority of w iggler radiation in the infrared region. Finally, the long wavelength radiation from the wiggler is compared with the undulator transition radiation and the ben ding magnetic edge emission. The result shows that long wavelength radiation fro m the wiggler is the strongest one.