Provide an automatic musical performance device, which is capable of giving a concert magic function in an acoustic instrument with a feeling of normally playing the acoustic instrument.A time period Tv between two points, and a tempo Tmp found based on a time intervals between two-point detection and later two-point detection, are found based on detection signals at the two points and later detection signals at the two points; and a delay time fD(Tv), which is from reception of each operating signal by a solenoid activating circuit 20 to commencement of a musical performance of an acoustic piano by the circuit 20, and a velocity value fv(Tv, Tmp) are found based on functions. A time period Ta, which starts at the time of later detection S.sub.1 in two-point detection as a reference and ends when a lever 19 is inverted, is found as fa(Tv) based on a function. Each operating signal is transmitted to the solenoid activating circuit 20 under such timing control that a transmission timing Ton comes at a time of lapse of "fa(Tv)-fD(Tv)" sec after the later detection; and the velocity value is set at fv(Tv, Tmp).