This study aims to understand what the causes, patterns and influences of hidden rules were for the recruitment process of private senior high and vocational schools. This was performed with interviews of a focus group composed of eight faculty members and three teachers from different institutions. From the research, it was found that some main causes of hidden rules were "a lack of flexibility and humanity in recruitment regulation, " "reasonable consensus and interest exchange from faculty members, " and "passive tolerance and private encouragement from school authority. " In addition, patterns of hidden rules included, "asking for an advance, " "delivery versus payment, " "defending each own turf, "and "grouping each own team. The influences behind the hidden rules were, "restoring the recruitment order and caring for the human sympathy, " "compromising the organizational interest and forming a popularity of factions, " and "causing damage to administration and leadership. "