Photoinduced reactions in Mg+-NH2CH3 and Mg+-NH (CH3)2 have been studied in the spectral range of 230-440nm. Although the N-H bond activation channel was found to be prominent in the photodissociation of Mg+-NH3 [Yoshida, Okai, and Fuke, Chem. Phys. Lett. 347, 93 (2001)], it is very unfavorable as the ammonia is replaced by methylamines in the complex. Instead, C-H bond cleavage products are observed from Mg+-NH(CH3)(CH2NH2+) and exclusively produced from Mg+-NH(CH3)2((CH3) HN+=CH2) after photoexcitation. For Mg+-NH2CH3, the C-N bond activation product Mg+NH2 and the charge transfer product CH3NH2+ are also abundant. The action spectra of the complexes consist of two pronounced peaks on the red and blue side of the Mg+3 2P←3 2S atomic transition. The calculated absorption spectra of the two complexes using the optimized structures of their ground states are in good agreement with the observed action spectra. On the basis of the branching fraction data and the calculated complex structures, the C-H bond activation is invoked to account for the MgH loss channel after photoexcitation, followed by a nonadiabatic transition to the ground state by a bond-stretch mechanism. However, the formation of Mg1NH2 from photodissociation of Mg+-NH2CH3 involves the insertion of Mg1 into the C-N bond. Finally, the photoinduced charge transfer product CH3NH21 are also identified from Mg+-NH2CH3 but not from Mg+-NH (CH3)2.