  The inner annular gap (IAG), a new type of inner gap whose magnetic field
lines intersect the null charge surface (NCS), is proposed to explain
$\gamma$-ray and radio emission from pulsars. The IAG can be an important
source for high-energy particles. The particles can radiate between the NCS and
the IAG. Some observational characteristics in both $\gamma$-ray and radio
bands, such as the $\gamma$-ray emission beams of Crab-like, Vela-like and
Geminga-like, can be reproduced by numerical method. It is predicted that the
view angle $\zeta$ should be larger than the inclination angle
($\zeta>\alpha$), otherwise the $\gamma$-ray radiation will have little
possibility to be observed. Whether the inner annular gap (or cap) is sparking
(or free flow) depends on the surface binding energy of the pulsar. In stead of
neutron star models, the scenario of the IAG is favorable for bare strange star
models, because bare strange stars can easily satisfy the requisite condition
to form an IAG for both pulsars ($\vec{\Omega}\cdot \vec{B}<0$) and
anti-pulsars ($\vec\Omega \cdot \vec{B}>0$).
