Of these cases, 16 of the investigations into civil servants within the department are ongoing.
The figures emerged after the Herald revealed earlier this month that a staff member at the department has been sacked for fraud.
The latest figures show that in the past five years, 49 civil servants working for the Department of Social Protection were investigated after allegations or concerns of fraud came to light.
However, despite the high number of investigations, only one staff member has been sacked as a result of a fraud investigation in the past five years. A second social welfare employee resigned in advance of being dismissed.
In the 31 remaining cases, investigations were carried out but no action was deemed necessary.
However, the department was unable to give details on how long the 16 ongoing investigations had been under way.
A spokesperson for the Department of Social Protection said that in any case of "substantiated fraud" it was the policy of the department that dismissal be sought.
They added that in no circumstances would employees be censured or have their pay grade cut as an alternative.
"The department has internal control procedures and guidelines. Where a staff member breaches these procedures they are dealt with in accordance with the Civil Service Disciplinary Code which can result in sanctions up to dismissal from the Civil Service. Where appropriate, cases are referred to the gardai," said the spokesperson.
A staff member was sacked in March after it was discovered that she had fraudulently diverted money into her own bank account and had awarded allowances to family members and friends.
She was found to be in breach of department rules on 13 occasions. The most serious issue was the diversion of a person's jobseeker's allowance payments into her own bank account
The issues came to light last year after investigators discovered irregularities during a probe.
The staff member met senior department officials in September last year when she was told she was suspected of mishandling taxpayers' money and breaching guidelines.
After being told that the incidents were considered a "serious misconduct" the employee was sacked.
The staff member appealed the decision to the Secretary General, requesting a "lesser penalty", however, this appeal was dismissed.