Medium energy gamma rays with Eγ=40–100 MeV following radiative capture of polarized protons on 11B and 12C were well studied by means of the HERMES. The angular distribution shows a uniform bell‐shape pattern, being independent of the final state. On the other hand the analyzing power depends on the spin direction with respect to the orbital angular momentum of the captured orbit. These results are well reproduced in terms of the stretched E1‐E2 radiations with the large E2 contributions for Eγ≳60 MeV. A simple geometrical consideration is given to account for the spin dependence of the analyzing power. Experimental results are compared with the Siegert theorem calculation and the model calculation including both the impulse term and the pion exchange term.