A power transmission apparatus comprising: a power transmission means (103, 106) configured to contactlessly transmit power to an electronic device; a communication means configured to communicate with the electronic device; and a control means, wherein the control means is configured to acquire information on a power level which is the maximum power receivable by the electronic device via the communication means, wherein the control means is configured to, in a case where an instruction for increasing or reducing the power transmitted from the power transmission means is received from the electronic device via the communication means change the power transmitted from the power transmission means (103, 106), and wherein an amount of the power changed by the control means at a time according to the instruction varies depending on the information on the power level which is the maximum power receivable by the electronic device, wherein the control means is configured to perform control such that before the power is transmitted to the electronic device by using the power transmission means, the information on the power level which is the maximum power receivable by the electronic device is acquired via the communication means, the apparatus being characterised in that: communication with the electronic device via the communication means is performed periodically at intervals, wherein the interval is adjusted based on the information on the power level, and wherein, the control means is configured to, in a case where a request to increase or reduce power is received from the electronic device via the communication means, receive information on the number of increase/reduction steps of power, and determine an increase/reduction amount per step of the power transmitted by the power transmission means depending on the determined power thereby determining a power increase/reduction amount. a power transmission means (103, 106) configured to contactlessly transmit power to an electronic device; a communication means configured to communicate with the electronic device; and a control means, wherein the control means is configured to acquire information on a power level which is the maximum power receivable by the electronic device via the communication means, wherein the control means is configured to, in a case where an instruction for increasing or reducing the power transmitted from the power transmission means is received from the electronic device via the communication means change the power transmitted from the power transmission means (103, 106), and wherein an amount of the power changed by the control means at a time according to the instruction varies depending on the information on the power level which is the maximum power receivable by the electronic device, wherein the control means is configured to perform control such that before the power is transmitted to the electronic device by using the power transmission means, the information on the power level which is the maximum power receivable by the electronic device is acquired via the communication means, the apparatus being characterised in that: communication with the electronic device via the communication means is performed periodically at intervals, wherein the interval is adjusted based on the information on the power level, and wherein, the control means is configured to, in a case where a request to increase or reduce power is received from the electronic device via the communication means, receive information on the number of increase/reduction steps of power, and determine an increase/reduction amount per step of the power transmitted by the power transmission means depending on the determined power thereby determining a power increase/reduction amount. communication with the electronic device via the communication means is performed periodically at intervals, wherein the interval is adjusted based on the information on the power level, and wherein, the control means is configured to, in a case where a request to increase or reduce power is received from the electronic device via the communication means, receive information on the number of increase/reduction steps of power, and determine an increase/reduction amount per step of the power transmitted by the power transmission means depending on the determined power thereby determining a power increase/reduction amount.