To provide speed controlling equipment of an engine for a snow plow which can reduce noise by decreasing engine speed when a load, which applies to a snow plow mechanism and a running mechanism, is little, and improve fuel consumption simultaneously, further, simplifies operation without using a regulation of the engine speed by manual actuation, and can stably execute load generating work such as snow plowing or running simultaneously.

An engine speed NE is controlled to a target revolution speed NED by driving a throttle valve by an electric motor, and the target revolution speed NED is raised to higher value (S22, S26, S30, S34) when an estimated engine output OP exceeds a first and a second threshold values of #OP12, #OP23 by estimating the engine output OP (S18) equivalent to the load acting to the snow plow mechanism and the running mechanism on the basis of a throttle opening θTH and the engine speed NE simultaneously.