According to a first aspect of the present invention, a content sharing support device includes a content receiving unit, a content transmitting unit, a first reaction receiving unit and a first reaction transmitting unit. The content receiving unit receives content from an online service providing device. The content transmitting unit transmits the content to a first terminal connected to the content sharing support device. The first reaction receiving unit receives a first reaction relating to the content from the first terminal. The first reaction transmitting unit transmits the first reaction to the online service providing device.