Even those already in senior management positions said they were not well-equipped with the necessary qualities, it found.
A survey conducted by the unit showed that 55 per cent of 107 middle managers who answered a questionnaire were interested in a senior management role. Only 41 per cent said they felt prepared to move upwards.
Karen Kerr, who is leading the research on succession planning in the colleges, commented: "This would indicate that there are significant numbers of college staff that are neither interested in progressing further nor prepared for a more senior role in colleges."
Ms Kerr told Broadcast, the SFEU journal: "The lack of interest in pursuing a more senior management role by middle managers limits the pool from which senior staff can be selected and is an issue that should be addressed and further explored.
"Perhaps the provision of professional development that enabled middle managers to learn more about the role of the senior manager would be one way to encourage further interest and improve perceptions of preparedness for more senior roles."
The SFEU survey found that 56 per cent of middle managers had fewer than seven days of professional development last year; 42 per cent had no leadership and management development; and 35 per cent had only one to three days' training.
Middle managers had limited experience of the different types of professional development available, the survey reported. Only 12 per cent had participated in mentoring, just 5 per cent had experienced a placement in another organisation and only 4 per cent had taken part in job shadowing in the past year.
More common were brief workshops or seminars, and "learning from experience".
Middle managers told the researchers their priority needs were for developing their financial and people skills. "Strong emphasis was placed on leadership development activities relating to setting targets for performance and accountability procedures," Ms Kerr said.
"The senior managers thought that the skill of people management was key to the senior management role. They also highlighted the importance of other skills such as finance, the development of a strategic awareness of the sector and the ability to interpret and implement sector policies."
Those in the top college posts suggested that development opportunities such as acting up, managing large teams and exposure to wider college issues had prepared them for their jobs and should be made available to middle managers.
Ms Kerr said more was needed. "The amount of professional development provided, the types of professional development accessed by middle managers and the topics of professional development undertaken should be reviewed."
She concluded: "As middle managers have a pivotal role in colleges, it is vital that they are sufficiently developed if their organisations are to achieve their strategic aims and provide a quality service for their learners.
"Development of middle managers is also important to ensure colleges have a pool of individuals from which senior staff can be selected."