The accident happened on Thursday night, the Blick newspaper reported quoting St Gallen police.
According to the police, the man lost his grip when climbing the wall without being adequately secured.
He fell ten metres and landed on the floor.
The injured indoor climber was taken to hospital.
The indoor climbing gym says under its terms and conditions on its website that the sport involves some risk and it takes no responsibility for injuries.
The staff are not obliged to ensure people are following the safety rules, it says.