We propose an integrate-and-fire neuron circuit and synaptic device with the floating body MOSFETs. The synaptic devices consist of a floating body MOSFET for biological synaptic characteristics. The synaptic learning is performed by hole accumulation. The synaptic device has short-term and long-term memory in a single silicon device [1]. I&F neuron circuit emulate the biological neuron characteristics such as integration, threshold triggering, output generation, and refractory period using floating body MOSFET [2]. The neuron circuit and the synaptic device are connected using current mirror circuit for summation of post synaptic pulses.