The multiphoton ionization mass spectrum of ethylamine in the 440-484 nm region is studied. The MPI process follows the molecular ion fragmentation pattern. Most of the molecular ions fragment by β-cleavage after they have been formed from (2+2) resonance-enhanced multiphoton ionization through 3s Rydberg state. The fragment ion CH2=N+H2 is most abundant. A part of molecule ions absorb one photon, then the C-H(CH2) bond cleavage gives CH3CH=N+H2 ions. The easiest fragmentation pathway of CH2=N+H2 and CH3CH=N+H2 is the loss of H2 molecule, procucing CH=N+H and C2H4N+ ions respectively.