A power conversion device comprising: a power transistor including a control input terminal, a first terminal, and a second terminal, which supplies electric power to a predetermined load through the first terminal and the second terminal; a driver that drives the control input terminal; a control device including a temperature estimation unit (PTJU), which controls on and off of the power transistor through the driver; and a voltage detection circuit (VDET) that detects an inter-terminal voltage of the first terminal and the second terminal during an on-period of the power transistor, wherein the temperature estimation unit (PTJU) previously holds correlation information between the inter-terminal voltage and inter-terminal current of the first terminal and second terminal and a junction temperature and estimates the junction temperature, based on the inter-terminal voltage obtained from the voltage detection circuit (VDET), a known inter-terminal current, and the correlation information, characterized in that: the correlation information has first correlation information corresponding to a case where the inter-terminal current flows from the first terminal to the second terminal and second correlation information corresponding to a case where the inter-terminal current flows from the second terminal to the first terminal, when the inter-terminal current flows from the first terminal to the second terminal, the temperature estimation unit (PTJU) uses the first correlation information to estimate the junction temperature, and when the inter-terminal current flows from the second terminal to the first terminal, the temperature estimation unit (PTJU) uses the second correlation information to estimate the junction temperature. a power transistor including a control input terminal, a first terminal, and a second terminal, which supplies electric power to a predetermined load through the first terminal and the second terminal; a driver that drives the control input terminal; a control device including a temperature estimation unit (PTJU), which controls on and off of the power transistor through the driver; and a voltage detection circuit (VDET) that detects an inter-terminal voltage of the first terminal and the second terminal during an on-period of the power transistor, wherein the temperature estimation unit (PTJU) previously holds correlation information between the inter-terminal voltage and inter-terminal current of the first terminal and second terminal and a junction temperature and estimates the junction temperature, based on the inter-terminal voltage obtained from the voltage detection circuit (VDET), a known inter-terminal current, and the correlation information, characterized in that: the correlation information has first correlation information corresponding to a case where the inter-terminal current flows from the first terminal to the second terminal and second correlation information corresponding to a case where the inter-terminal current flows from the second terminal to the first terminal, when the inter-terminal current flows from the first terminal to the second terminal, the temperature estimation unit (PTJU) uses the first correlation information to estimate the junction temperature, and when the inter-terminal current flows from the second terminal to the first terminal, the temperature estimation unit (PTJU) uses the second correlation information to estimate the junction temperature. the correlation information has first correlation information corresponding to a case where the inter-terminal current flows from the first terminal to the second terminal and second correlation information corresponding to a case where the inter-terminal current flows from the second terminal to the first terminal, when the inter-terminal current flows from the first terminal to the second terminal, the temperature estimation unit (PTJU) uses the first correlation information to estimate the junction temperature, and when the inter-terminal current flows from the second terminal to the first terminal, the temperature estimation unit (PTJU) uses the second correlation information to estimate the junction temperature.