Based on the basic concept of modal pushover analysis (MPA), details of MPA estimating irregular continuous bridges’ seismic displacement demand were investigated. Analyzing on bridge’s displacement monitoring point’s selection, capacity spectrum form, inelastic demand spectrum’s building process and modal combination rules produced a MPA procedure for irregular continuous bridges. The lateral seismic displacement demand of four irregular continuous bridges estimated by the MPA procedure was compared with rigorous inelastic time-history analysis. Results show, although irregular continuous bridges’ important modes couple with each other after piers yield, the MPA procedure can estimate reasonable seismic displacement demand.