An abnormality sensing device able to detect a leak in a passage connecting a purge control valve to an intake passage of an internal combustion engine for an evaporation fuel purge system comprising: a fuel tank storing fuel; a canister that adsorbs evaporation fuel generated in the fuel tank and that desorbs the evaporation fuel; an intake passage of an internal combustion engine in which the evaporation fuel desorbed from the canister is mixed with fuel for combustion to be combusted; a purge passage that connects the canister to the intake passage of the internal combustion engine; a purge pump that pumps the evaporation fuel from the canister to the intake passage of the internal combustion engine; a purge control valve disposed in the purge passage to control a flow of the evaporation fuel pumped by the purge pump to flow through the purge passage; a valve component being an electromagnetic valve that closes and opens the purge passage to control the evaporation fuel to flow into the intake passage of the internal combustion engine at a target passage (18a, 18b) of the purge passage, the target passage (18a, 18b) including at least a first purge passage defined between the purge control valve and the intake passage of the internal combustion engine, the purge passage comprising a second purge passage, the purge pump and the purge control valve being connected with each other by the second purge passage, the purge passage further comprising a third purge passage, wherein an end of piping which defines the third purge passage is connected to the outflow part of the canister and the other end of the piping which defines the third purge passage is connected to the inflow part of the purge pump; and an abnormality determining portion that determines whether there is an abnormality in the evaporation fuel purge system in a state where the evaporation fuel is pumped by the purge pump toward the intake passage of the internal combustion engine, wherein the abnormality determining portion is in a determination possible state when the evaporation fuel is pumped toward the intake passage of the internal combustion engine by the purge pump, when the purge control valve allows the evaporation fuel to flow through the first purge passage, and when the valve component prohibits the evaporation fuel from being supplied to the intake passage of the internal combustion engine, and the abnormality determining portion detects a predetermined physical quantity relevant to a pressure change in the target passage (18a, 18b) in the determination possible state, and determines whether there is an abnormality in the evaporation fuel purge system according to the predetermined physical quantity. a fuel tank storing fuel; a canister that adsorbs evaporation fuel generated in the fuel tank and that desorbs the evaporation fuel; an intake passage of an internal combustion engine in which the evaporation fuel desorbed from the canister is mixed with fuel for combustion to be combusted; a purge passage that connects the canister to the intake passage of the internal combustion engine; a purge pump that pumps the evaporation fuel from the canister to the intake passage of the internal combustion engine; a purge control valve disposed in the purge passage to control a flow of the evaporation fuel pumped by the purge pump to flow through the purge passage; a valve component being an electromagnetic valve that closes and opens the purge passage to control the evaporation fuel to flow into the intake passage of the internal combustion engine at a target passage (18a, 18b) of the purge passage, the target passage (18a, 18b) including at least a first purge passage defined between the purge control valve and the intake passage of the internal combustion engine, the purge passage comprising a second purge passage, the purge pump and the purge control valve being connected with each other by the second purge passage, the purge passage further comprising a third purge passage, wherein an end of piping which defines the third purge passage is connected to the outflow part of the canister and the other end of the piping which defines the third purge passage is connected to the inflow part of the purge pump; and an abnormality determining portion that determines whether there is an abnormality in the evaporation fuel purge system in a state where the evaporation fuel is pumped by the purge pump toward the intake passage of the internal combustion engine, wherein the abnormality determining portion is in a determination possible state when the evaporation fuel is pumped toward the intake passage of the internal combustion engine by the purge pump, when the purge control valve allows the evaporation fuel to flow through the first purge passage, and when the valve component prohibits the evaporation fuel from being supplied to the intake passage of the internal combustion engine, and the abnormality determining portion detects a predetermined physical quantity relevant to a pressure change in the target passage (18a, 18b) in the determination possible state, and determines whether there is an abnormality in the evaporation fuel purge system according to the predetermined physical quantity.