Musical instrument and musical instrument cooperation program

The present invention addresses the problem of providing an interface with good operability to a player in a musical instrument having a plurality of operation methods. An electronic keyboard musical instrument (1) includes a keyboard (11) that receives a musical performance operation. The electronic keyboard musical instrument (1) further includes a plurality of operation units (12B) that receive an operation except for the musical performance operation with respect to the electronic keyboard musical instrument (1), and a disabler (112) that disables operational input in at least one operation unit (12B) among the plurality of operation units (12B) when a connection with a tablet for inputting an operation with respect to the electronic keyboard musical instrument (1) is established. 本发明的课题在于，在存在多个操作方法的乐器中，对演奏者提供操作性良好的接口。电子键盘乐器(1)具有接受演奏操作的键盘(11)。电子键盘乐器(1)还具有：多个操作部(12B)，它们接受除了针对电子键盘乐器(1)的演奏操作以外的操作；以及无效化部(112)，其在建立了与用于输入针对电子键盘乐器(1)的操作的平板(5)的连接时，将多个操作部(12B)之中的至少1个操作部(12B)的操作输入无效化。