A reliability analyzing system for manufacturing processes is disclosed, which comprises a computer system provided with a data memory device, a central processing device and input/output devices, terminals which input/output information into/from said computer system, and output devices for manufacturing sites; whereby said data memory device stores required specifications for each product, works for manufacturing and controlling processes, information relating to items, such as required specifications, works, control items, etc. and information mutually relating different items, and on the basis of the stored information, reliability analysis for each process is effected for all the processes and reliability analysis for each required specification is performed for all the required specifications.