Single pion photoproduction in the first resonance region is investigated on the basis of noe-particle-exchange model. In addition to the Born terms, s-, t- and u-channel exchanges of N11, ∆33, N13, ρ and ω are taken into consideration. In order to guarantee the unitarity we use the K-matrix method. The coupling constants and off-mass-shell parameters are determined by χ2-fit. The coupling constants obtained are consistent with the values estimated by the use of the radiative decay widths and the results of low energy pion-nucleon or nucleon-nucleon analyses. Our predicted multipoles are in fairly good agreement with the experiments. ∆33 contribution is dominant to M1+(3/2) and is very small to E1+(3/2). The main contribution to E1+(3/2) is due to the Born terms and the double zero observed in this multipole is well reproduced by incorporating unitarity. ρ exchange is positively required to explain the absolute value and energy dependence of E0+(0). It is difficult to reproduce the characteristic feature of nM1-(1/2). It was argued that this structure will show the onset of N11 resonance. However, its contribution is too small to support this argument.