A power trading assistance device comprising: a player behavior predicting unit that predicts behavior of a player and calculates an order receiving and placing information prediction value; a market physical restriction predicting unit that predicts a power transportation path state, including interconnection line empty capacity which indicates power transmission capacity between areas, and calculates a power transportation path state prediction value; and a market predicting unit that predicts a market price based on the order receiving and placing information prediction value and the power transportation path state prediction value, wherein the market predicting unit includes: a trading area fragmentation predicting unit that predicts whether market fragmentation between areas occurs based on a power demand amount for each area in a prediction target period, which is calculated by the player behavior predicting unit as the order receiving and placing information prediction value, a power supply amount for each area in the prediction target period, and the power transportation path state prediction value, wherein market fragmentation occurs when a planned value of a power interchange amount between areas exceeds interconnection line empty capacity between the areas, and a market price predicting unit that calculates a market price prediction value indicating a market price in each area in the prediction target period based on a prediction result from the trading area fragmentation predicting unit, wherein the trading area fragmentation predicting unit identifies a pattern of market fragmentation for each predetermined time, which has occurred in the past, based on a market fragmentation pattern actual value indicating a past market fragmentation pattern actual result between areas, and identifies the pattern of market fragmentation of the prediction target period based on attribute information, which is a factor of generating the pattern of market fragmentation in each time range, and attribute information on the prediction target period, and wherein the attribute information comprises a temperature. a player behavior predicting unit that predicts behavior of a player and calculates an order receiving and placing information prediction value; a market physical restriction predicting unit that predicts a power transportation path state, including interconnection line empty capacity which indicates power transmission capacity between areas, and calculates a power transportation path state prediction value; and a market predicting unit that predicts a market price based on the order receiving and placing information prediction value and the power transportation path state prediction value, wherein the market predicting unit includes: a trading area fragmentation predicting unit that predicts whether market fragmentation between areas occurs based on a power demand amount for each area in a prediction target period, which is calculated by the player behavior predicting unit as the order receiving and placing information prediction value, a power supply amount for each area in the prediction target period, and the power transportation path state prediction value, wherein market fragmentation occurs when a planned value of a power interchange amount between areas exceeds interconnection line empty capacity between the areas, and a market price predicting unit that calculates a market price prediction value indicating a market price in each area in the prediction target period based on a prediction result from the trading area fragmentation predicting unit, a trading area fragmentation predicting unit that predicts whether market fragmentation between areas occurs based on a power demand amount for each area in a prediction target period, which is calculated by the player behavior predicting unit as the order receiving and placing information prediction value, a power supply amount for each area in the prediction target period, and the power transportation path state prediction value, wherein market fragmentation occurs when a planned value of a power interchange amount between areas exceeds interconnection line empty capacity between the areas, and a market price predicting unit that calculates a market price prediction value indicating a market price in each area in the prediction target period based on a prediction result from the trading area fragmentation predicting unit, wherein the trading area fragmentation predicting unit identifies a pattern of market fragmentation for each predetermined time, which has occurred in the past, based on a market fragmentation pattern actual value indicating a past market fragmentation pattern actual result between areas, and identifies the pattern of market fragmentation of the prediction target period based on attribute information, which is a factor of generating the pattern of market fragmentation in each time range, and attribute information on the prediction target period, and wherein the attribute information comprises a temperature.