Power transmission device

A power transmission device, comprising:

• a case including a first oil reservoir configured to store oil, a second oil reservoir configured to store the oil, and a partition wall configured to separate the first oil reservoir and the second oil reservoir from each other;
• the oil enclosed in the case;
• a rotating member configured to contact the oil in the first oil reservoir;
• an opening and closing member located in the partition wall and configured to supply the oil from the second oil reservoir to the first oil reservoir;
• an oil cooler located outside the case and configured to cool the oil by causing the oil and a cooling medium to exchange heat with each other;
• and
• a control unit configured to control opening and closing of the opening and closing member, wherein
• an oil level in the first oil reservoir when the opening and closing member is open is higher than an oil level in the first oil reservoir when the opening and closing member is closed, and is high enough for at least a part of the rotating member to be dipped in the oil, and
• the control unit is configured to open the opening and closing member when the control unit receives a request from a device to which the cooling medium flowing out of the oil cooler is to be supplied.